Reuse token lookup visitor across AST descent by Tom4ikss · Pull Request #64928 · microsoft/TypeScript

Tom S (Tom4ikss) · 2026-10-22T19:51:19Z

getTokenAtPosition allocates a NodeVisitor and its hooks at each step down the tree. This change reuses one visitor for the duration of each lookup. Child and JSDoc traversal stay the same, and VisitEachChildAndJSDoc keeps its signature. Separate lookups still have separate visitors.

Profiling a tool that makes native API type queries showed repeated visitor allocations in token lookup. This patch did not produce a clear timing improvement in the full workload.

The benchmark looks up an identifier inside 24 nested calls. These are medians of five runs on Go 1.27.1 / darwin-arm64 / Apple M3 Pro:

	Before	After
Time	6.87 µs/op	1.24 µs/op
Allocated bytes	41,536 B/op	1,664 B/op
Allocations	153/op	13/op

The numbers cover this token lookup only. They do not measure overall compiler performance.

Validation on Node 24.22.1 and npm 11.19.1:

npx hereby generate
npx hereby validate --all
npx hereby test:benchmarks
npx hereby test:benchmarks:api
npm run -w @typescript/typescript build
npm run -w native-preview build
npx hereby check:format

All passed. The tidy checks for both Go modules and go work sync also passed, with a clean working tree afterwards.

To compare the benchmark with the parent revision, apply only the benchmark addition and run this from tsc/:

go test ./internal/astnav -run '^$' -bench BenchmarkGetTokenAtPositionNested -benchmem -count=5

Fixes #64929.

AI assistance: Codex assisted in authoring and testing this patch.

Tom S (Tom4ikss) · 2026-10-22T20:12:55Z

@microsoft-github-policy-service agree

Jake Bailey (jakebailey) · 2026-10-22T20:14:30Z

This is a microbenchmark but how did you decide to try and work on this?

typescript-automation · 2026-10-22T20:18:59Z

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

Copilot

🟢 Approval recommended

The localized refactor preserves traversal behavior and per-lookup isolation, with no unresolved findings.

No open issues 🎉

What changed in this PR

Reduces allocation overhead in AST token lookup by reusing one visitor throughout each lookup, while preserving traversal behavior and the public helper signature.

Changes:

Moves visitor creation outside the descent loop and introduces an internal helper accepting that visitor.
Adds a nested-call benchmark to measure token lookup time and allocations.

File	Description
`tsc/internal/astnav/tokens.go`	Reuses a lookup-local visitor without changing child or JSDoc traversal.
`tsc/internal/astnav/tokens_test.go`	Adds a token lookup benchmark with 24 nested calls.

_{Review effort: Balanced}

Tom S (Tom4ikss) · 2026-10-22T20:34:47Z

I'm working on a build-time i18n plugin that uses literal unions and template literal types to narrow down which translation keys each bundle needs. Type analysis is the slowest phase of the existing plugin, so I'm experimenting with native API type queries to reduce that cost.

Repeated visitor construction in token lookup showed up in an allocation profile, so I isolated it in this benchmark. I haven't seen a clear timing improvement in the full workload from this patch. The results so far show lower allocations and faster lookups in the microbenchmark.

Daniel Rosenwasser (DanielRosenwasser) · 2026-10-29T06:46:17Z

TypeScript Bot (@typescript-bot) perf test this

typescript-automation · 2026-10-29T06:46:23Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`perf test this`	✅ Started	👀 Results

typescript-automation · 2026-10-29T07:34:07Z

Daniel Rosenwasser (@DanielRosenwasser)
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_88,466	_88,466	_~	_~	_~	_{p=1.000 n=20}
_Types	_79,607	_79,607	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{104,132k (± 0.03%)}	_{104,141k (± 0.03%)}	_~	_104,028k	_104,267k	_{p=0.723 n=20}
_{Memory Allocs}	_{2,200,931 (± 0.00%)}	_{2,200,943 (± 0.00%)}	_~	_2,200,624	_2,201,382	_{p=0.989 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.025s (± 3.09%)}	_{0.025s (± 2.35%)}	_~	_0.022s	_0.028s	_{p=0.914 n=20}
_{Bind Time}	_{0.009s (± 4.87%)}	_{0.009s (± 5.70%)}	_~	_0.007s	_0.012s	_{p=0.194 n=20}
_{Check Time}	_{0.230s (± 1.22%)}	_{0.228s (± 0.55%)}	_~	_0.224s	_0.235s	_{p=0.315 n=20}
_{Emit Time}	_{0.160s (± 3.40%)}	_{0.155s (± 1.04%)}	_{🟩-0.005s (- 3.30%)}	_0.147s	_0.163s	_{p=0.005 n=20}
_{Total Time}	_{0.427s (± 1.80%)}	_{0.420s (± 0.49%)}	_{-0.007s (- 1.56%)}	_0.414s	_0.432s	_{p=0.006 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_{586,526 (± 0.02%)}	_{586,522 (± 0.02%)}	_~	_586,049	_586,736	_{p=1.000 n=20}
_Types	_{241,687 (± 0.00%)}	_{241,688 (± 0.00%)}	_~	_241,685	_241,695	_{p=0.116 n=20}
_{Memory Used}	_{517,974k (± 0.02%)}	_{517,945k (± 0.02%)}	_~	_517,666k	_518,292k	_{p=0.640 n=20}
_{Memory Allocs}	_{13,113,599 (± 0.02%)}	_{13,118,066 (± 0.03%)}	_{+4,467 (+ 0.03%)}	_13,110,361	_13,141,118	_{p=0.005 n=20}
_{Config Time}	_{0.008s (± 1.30%)}	_{0.008s (± 1.77%)}	_~	_0.008s	_0.009s	_{p=1.000 n=20}
_{Parse Time}	_{0.131s (± 1.48%)}	_{0.131s (± 2.48%)}	_~	_0.122s	_0.149s	_{p=0.550 n=20}
_{Bind Time}	_{0.042s (± 6.49%)}	_{0.044s (± 7.54%)}	_~	_0.039s	_0.060s	_{p=0.518 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.926s (± 1.28%)}	_{0.940s (± 4.85%)}	_~	_0.896s	_1.348s	_{p=0.673 n=20}
_{Total Time}	_{1.118s (± 1.06%)}	_{1.136s (± 4.13%)}	_~	_1.085s	_1.559s	_{p=0.867 n=20}
_{arktype - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_685,920	_685,920	_~	_~	_~	_{p=1.000 n=20}
_Types	_939,467	_939,467	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{497,239k (± 0.01%)}	_{497,280k (± 0.01%)}	_~	_497,046k	_497,446k	_{p=0.194 n=20}
_{Memory Allocs}	_{12,805,091 (± 0.01%)}	_{12,806,082 (± 0.02%)}	_~	_12,801,380	_12,816,208	_{p=0.565 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.044s (± 4.14%)}	_{0.044s (± 3.74%)}	_~	_0.038s	_0.051s	_{p=0.804 n=20}
_{Bind Time}	_{0.013s (± 6.92%)}	_{0.013s (± 8.75%)}	_~	_0.011s	_0.020s	_{p=0.677 n=20}
_{Check Time}	_{0.992s (± 0.75%)}	_{0.988s (± 0.68%)}	_~	_0.962s	_1.021s	_{p=0.409 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.081s (± 0.63%)}	_{1.077s (± 0.62%)}	_~	_1.053s	_1.110s	_{p=0.473 n=20}
_{class-transformer - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_45,376	_45,376	_~	_~	_~	_{p=1.000 n=20}
_Types	_7,573	_7,573	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{27,838k (± 0.02%)}	_{27,836k (± 0.03%)}	_~	_27,811k	_27,864k	_{p=0.693 n=20}
_{Memory Allocs}	_{323,469 (± 0.05%)}	_{323,303 (± 0.04%)}	_~	_322,920	_323,911	_{p=0.136 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.012s (± 5.67%)}	_{0.011s (± 4.86%)}	_~	_0.009s	_0.013s	_{p=0.095 n=20}
_{Bind Time}	_{0.003s (±17.34%)}	_{0.004s (±15.06%)}	_~	_0.002s	_0.005s	_{p=0.240 n=20}
_{Check Time}	_{0.008s (± 4.45%)}	_{0.008s (± 4.98%)}	_~	_0.007s	_0.009s	_{p=0.080 n=20}
_{Emit Time}	_{0.010s (± 4.14%)}	_{0.010s (± 3.93%)}	_~	_0.008s	_0.011s	_{p=0.480 n=20}
_{Total Time}	_{0.034s (± 2.12%)}	_{0.034s (± 1.83%)}	_~	_0.031s	_0.036s	_{p=0.170 n=20}
_{effect - native}
_Errors	₁₂	₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,235,115	_1,235,115	_~	_~	_~	_{p=1.000 n=20}
_Types	_894,113	_894,113	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{940,583k (± 0.03%)}	_{940,627k (± 0.02%)}	_~	_939,719k	_941,479k	_{p=0.678 n=20}
_{Memory Allocs}	_{15,753,633 (± 0.01%)}	_{15,752,298 (± 0.02%)}	_~	_15,743,204	_15,767,117	_{p=0.461 n=20}
_{Config Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.159s (± 1.59%)}	_{0.161s (± 1.61%)}	_~	_0.151s	_0.175s	_{p=0.255 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.968s (± 0.82%)}	_{0.975s (± 0.81%)}	_~	_0.948s	_1.007s	_{p=0.273 n=20}
_{Emit Time}	_{0.527s (± 1.56%)}	_{0.517s (± 1.54%)}	_~	_0.491s	_0.556s	_{p=0.068 n=20}
_{Total Time}	_{1.752s (± 0.52%)}	_{1.747s (± 0.65%)}	_~	_1.692s	_1.792s	_{p=0.784 n=20}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_3,784,019	_3,784,019	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,355,974	_1,355,974	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,835,621k (± 0.07%)}	_{1,835,627k (± 0.07%)}	_~	_1,831,202k	_1,842,293k	_{p=0.889 n=20}
_{Memory Allocs}	_{26,746,093 (± 0.07%)}	_{26,733,475 (± 0.05%)}	_~	_26,702,713	_26,806,939	_{p=0.127 n=20}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.286s (± 2.00%)}	_{0.298s (± 3.34%)}	_~	_0.272s	_0.348s	_{p=0.176 n=20}
_{Bind Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{3.268s (± 0.38%)}	_{3.267s (± 0.42%)}	_~	_3.225s	_3.315s	_{p=0.867 n=20}
_{Emit Time}	_{0.251s (± 1.29%)}	_{0.250s (± 0.94%)}	_~	_0.241s	_0.257s	_{p=0.899 n=20}
_{Total Time}	_{4.311s (± 0.48%)}	_{4.312s (± 0.38%)}	_~	_4.247s	_4.401s	_{p=0.490 n=20}
_{sentry - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,793,245	_4,793,245	_~	_~	_~	_{p=1.000 n=20}
_Types	_2,607,047	_2,607,047	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,880,437k (± 0.03%)}	_{2,881,031k (± 0.03%)}	_~	_2,878,755k	_2,884,216k	_{p=0.383 n=20}
_{Memory Allocs}	_{75,892,358 (± 0.10%)}	_{75,951,488 (± 0.05%)}	_~	_75,750,689	_76,106,934	_{p=0.620 n=20}
_{Config Time}	_{0.027s (± 0.91%)}	_{0.027s (± 1.25%)}	_~	_0.025s	_0.028s	_{p=0.452 n=20}
_{Parse Time}	_{0.545s (± 7.10%)}	_{0.485s (± 2.73%)}	_{🟩-0.060s (-11.02%)}	_0.443s	_0.558s	_{p=0.010 n=20}
_{Bind Time}	_{0.162s (±10.04%)}	_{0.176s (± 9.80%)}	_~	_0.137s	_0.240s	_{p=0.159 n=20}
_{Check Time}	_{7.257s (± 0.69%)}	_{7.211s (± 1.13%)}	_~	_6.874s	_7.436s	_{p=0.547 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{8.042s (± 0.84%)}	_{7.952s (± 1.07%)}	_~	_7.558s	_8.212s	_{p=0.183 n=20}
_{social-app - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,883,074	_1,883,074	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,158,170	_1,158,170	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{972,545k (± 0.02%)}	_{972,505k (± 0.02%)}	_~	_971,839k	_973,336k	_{p=0.542 n=20}
_{Memory Allocs}	_{13,720,144 (± 0.21%)}	_{13,745,139 (± 0.17%)}	_~	_13,666,828	_13,836,632	_{p=0.068 n=20}
_{Config Time}	_{0.008s (± 2.10%)}	_{0.008s (± 1.30%)}	_~	_0.008s	_0.009s	_{p=0.605 n=20}
_{Parse Time}	_{0.166s (± 2.63%)}	_{0.171s (± 3.70%)}	_~	_0.154s	_0.208s	_{p=0.365 n=20}
_{Bind Time}	_{0.049s (±11.20%)}	_{0.048s (±10.66%)}	_~	_0.037s	_0.067s	_{p=0.614 n=20}
_{Check Time}	_{1.660s (± 0.61%)}	_{1.659s (± 0.63%)}	_~	_1.608s	_1.705s	_{p=0.899 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.902s (± 0.64%)}	_{1.905s (± 0.72%)}	_~	_1.854s	_1.963s	_{p=0.846 n=20}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,184,972	_1,184,972	_~	_~	_~	_{p=1.000 n=20}
_Types	_438,963	_438,963	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,172,549k (± 0.23%)}	_{1,170,473k (± 0.31%)}	_~	_1,153,966k	_1,183,413k	_{p=0.883 n=20}
_{Memory Allocs}	_{77,474,976 (± 0.10%)}	_{77,475,331 (± 0.13%)}	_~	_76,900,573	_77,727,337	_{p=0.841 n=20}
_{Config Time}	_{0.002s (±15.73%)}	_{0.002s (± 9.43%)}	_~	_0.001s	_0.003s	_{p=0.615 n=20}
_{Parse Time}	_{0.150s (± 1.70%)}	_{0.146s (± 1.84%)}	_~	_0.135s	_0.155s	_{p=0.068 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.851s (± 0.93%)}	_{0.846s (± 0.62%)}	_~	_0.827s	_0.872s	_{p=0.560 n=20}
_{Emit Time}	_{0.179s (± 1.81%)}	_{0.179s (± 1.69%)}	_~	_0.166s	_0.193s	_{p=0.846 n=20}
_{Total Time}	_{10.342s (± 0.86%)}	_{10.285s (± 0.58%)}	_~	_10.045s	_10.533s	_{p=0.723 n=20}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_263,511	_263,511	_~	_~	_~	_{p=1.000 n=20}
_Types	_196,116	_196,116	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{224,616k (± 0.02%)}	_{224,601k (± 0.02%)}	_~	_224,410k	_224,743k	_{p=0.597 n=20}
_{Memory Allocs}	_{4,304,849 (± 0.01%)}	_{4,304,976 (± 0.01%)}	_~	_4,303,272	_4,306,753	_{p=0.738 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.052s (± 3.09%)}	_{0.053s (± 3.09%)}	_~	_0.047s	_0.060s	_{p=0.866 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.410s (± 0.73%)}	_{0.412s (± 1.61%)}	_~	_0.394s	_0.450s	_{p=0.973 n=20}
_{Emit Time}	_{0.084s (± 3.46%)}	_{0.082s (± 2.37%)}	_~	_0.074s	_0.092s	_{p=0.290 n=20}
_{Total Time}	_{0.577s (± 0.58%)}	_{0.577s (± 1.19%)}	_~	_0.561s	_0.613s	_{p=0.379 n=20}
_{t3code-server - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,350,661	_4,350,661	_~	_~	_~	_{p=1.000 n=20}
_Types	_3,040,647	_3,040,647	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,433,888k (± 0.03%)}	_{2,434,038k (± 0.03%)}	_~	_2,431,734k	_2,437,349k	_{p=0.779 n=20}
_{Memory Allocs}	_{37,868,293 (± 0.04%)}	_{37,889,354 (± 0.05%)}	_~	_37,826,172	_38,002,889	_{p=0.081 n=20}
_{Config Time}	_0.003s	_{0.003s (± 3.54%)}	_~	_0.002s	_0.003s	_{p=1.000 n=20}
_{Parse Time}	_{0.273s (± 2.23%)}	_{0.270s (± 2.17%)}	_~	_0.245s	_0.294s	_{p=0.357 n=20}
_{Bind Time}	_{0.093s (± 8.71%)}	_{0.094s (± 8.90%)}	_~	_0.081s	_0.141s	_{p=0.672 n=20}
_{Check Time}	_{8.104s (± 1.02%)}	_{8.122s (± 1.17%)}	_~	_7.769s	_8.498s	_{p=0.703 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{8.484s (± 1.02%)}	_{8.500s (± 1.13%)}	_~	_8.134s	_8.869s	_{p=0.764 n=20}
_{tanstack-router - native}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_571,756	_571,756	_~	_~	_~	_{p=1.000 n=20}
_Types	_397,689	_397,689	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{331,461k (± 0.01%)}	_{331,438k (± 0.01%)}	_~	_331,251k	_331,667k	_{p=0.542 n=20}
_{Memory Allocs}	_{5,099,615 (± 0.15%)}	_{5,093,499 (± 0.05%)}	_~	_5,087,575	_5,112,085	_{p=0.114 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.042s (± 3.99%)}	_{0.044s (± 3.83%)}	_~	_0.039s	_0.049s	_{p=0.391 n=20}
_{Bind Time}	_{0.014s (±11.69%)}	_{0.012s (± 7.89%)}	_~	_0.011s	_0.018s	_{p=0.113 n=20}
_{Check Time}	_{0.585s (± 0.93%)}	_{0.582s (± 0.82%)}	_~	_0.563s	_0.604s	_{p=0.291 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.665s (± 0.70%)}	_{0.667s (± 0.85%)}	_~	_0.640s	_0.686s	_{p=0.387 n=20}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_231,616	_231,616	_~	_~	_~	_{p=1.000 n=20}
_Types	_181,195	_181,195	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{193,545k (± 0.01%)}	_{193,552k (± 0.02%)}	_~	_193,454k	_193,669k	_{p=0.723 n=20}
_{Memory Allocs}	_{1,373,495 (± 0.02%)}	_{1,373,375 (± 0.01%)}	_~	_1,372,814	_1,374,386	_{p=0.465 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.047s (± 2.91%)}	_{0.047s (± 2.55%)}	_~	_0.041s	_0.050s	_{p=0.641 n=20}
_{Bind Time}	_{0.023s (±13.02%)}	_{0.022s (± 4.66%)}	_~	_0.020s	_0.027s	_{p=0.919 n=20}
_{Check Time}	_{0.324s (± 2.09%)}	_{0.322s (± 1.02%)}	_~	_0.307s	_0.333s	_{p=0.815 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.400s (± 2.33%)}	_{0.397s (± 0.86%)}	_~	_0.378s	_0.408s	_{p=0.634 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,414,524	_7,414,524	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,356,679	_4,356,679	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{5,151,228k (± 0.02%)}	_{5,151,618k (± 0.02%)}	_~	_5,148,269k	_5,155,258k	_{p=0.640 n=20}
_{Memory Allocs}	_{65,097,340 (± 0.03%)}	_{65,092,666 (± 0.02%)}	_~	_65,073,767	_65,158,755	_{p=0.758 n=20}
_{Config Time}	_{0.034s (± 1.25%)}	_{0.034s (± 1.29%)}	_~	_0.033s	_0.036s	_{p=0.655 n=20}
_{Parse Time}	_{0.950s (± 1.90%)}	_{0.951s (± 2.61%)}	_~	_0.860s	_1.076s	_{p=0.836 n=20}
_{Bind Time}	_{0.313s (± 3.38%)}	_{0.322s (± 5.79%)}	_~	_0.296s	_0.467s	_{p=0.794 n=20}
_{Check Time}	_{7.704s (± 1.04%)}	_{7.667s (± 0.85%)}	_~	_7.484s	_7.984s	_{p=0.588 n=20}
_{Emit Time}	_{2.951s (± 4.08%)}	_{2.963s (± 4.63%)}	_~	_2.755s	_3.752s	_{p=0.763 n=20}
_{Total Time}	_{12.015s (± 1.08%)}	_{11.998s (± 1.37%)}	_~	_11.555s	_12.787s	_{p=0.644 n=20}
_{webpack - native}
_Errors	₆₁₉	₆₁₉	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_926,331	_926,331	_~	_~	_~	_{p=1.000 n=20}
_Types	_646,440	_646,440	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{698,502k (± 0.01%)}	_{698,603k (± 0.01%)}	_~	_698,264k	_698,945k	_{p=0.127 n=20}
_{Memory Allocs}	_{6,690,874 (± 0.04%)}	_{6,689,327 (± 0.03%)}	_~	_6,685,053	_6,704,623	_{p=0.183 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.149s (± 3.67%)}	_{0.151s (± 3.39%)}	_~	_0.133s	_0.172s	_{p=0.569 n=20}
_{Bind Time}	_{0.048s (± 8.07%)}	_{0.049s (± 7.69%)}	_~	_0.041s	_0.069s	_{p=0.692 n=20}
_{Check Time}	_{1.279s (± 1.00%)}	_{1.272s (± 1.16%)}	_~	_1.231s	_1.320s	_{p=0.516 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.507s (± 1.19%)}	_{1.501s (± 1.04%)}	_~	_1.458s	_1.558s	_{p=0.606 n=20}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_640,490	_640,490	_~	_~	_~	_{p=1.000 n=20}
_Types	_387,988	_387,988	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{350,937k (± 0.02%)}	_{350,993k (± 0.03%)}	_~	_350,713k	_351,457k	_{p=0.445 n=20}
_{Memory Allocs}	_{4,069,686 (± 0.05%)}	_{4,066,055 (± 0.08%)}	_{-3,631 (- 0.09%)}	_4,053,618	_4,080,050	_{p=0.040 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.063s (± 2.41%)}	_{0.061s (± 2.89%)}	_{🟩-0.002s (- 3.25%)}	_0.056s	_0.071s	_{p=0.025 n=20}
_{Bind Time}	_{0.018s (± 9.96%)}	_{0.019s (± 8.10%)}	_~	_0.017s	_0.027s	_{p=0.150 n=20}
_{Check Time}	_{0.413s (± 0.67%)}	_{0.413s (± 0.75%)}	_~	_0.403s	_0.425s	_{p=0.963 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.501s (± 0.93%)}	_{0.500s (± 0.67%)}	_~	_0.490s	_0.512s	_{p=0.952 n=20}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
arktype - native
class-transformer - native
effect - native
mui-docs - native
sentry - native
social-app - native
strada-build-src - native
strada-compiler - native
t3code-server - native
tanstack-router - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₂₀
_Baseline	_baseline	₂₀

lsp

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{CompilerLSP - native}
_{Req 1 - updateOpen}	_{5ms (±16.88%)}	_{5ms (±13.53%)}	_~	_4ms	_8ms	_{p=1.000 n=20}
_{Req 2 - geterr}	_{152ms (± 0.61%)}	_{153ms (± 0.87%)}	_~	_149ms	_160ms	_{p=0.202 n=20}
_{Req 3 - references}	_{30ms (± 2.40%)}	_{26ms (± 1.75%)}	_{🟩-4ms (-13.04%)}	_25ms	_29ms	_{p=0.000 n=20}
_{Req 4 - navto}	_{14ms (± 5.03%)}	_{13ms (± 2.02%)}	_{🟩-1ms (- 6.81%)}	_12ms	_14ms	_{p=0.023 n=20}
_{Req 5 - completionInfo count}	_1,525	_1,525	_~	_~	_~	_{p=1.000 n=20}
_{Req 5 - completionInfo}	_{9ms (±12.38%)}	_{12ms (± 9.44%)}	_{🔻+2ms (+25.00%)}	_8ms	_14ms	_{p=0.003 n=20}
_{Compiler-UnionsLSP - native}
_{Req 1 - updateOpen}	_{5ms (±13.70%)}	_{5ms (±11.27%)}	_~	_4ms	_7ms	_{p=0.932 n=20}
_{Req 2 - geterr}	_{256ms (± 0.42%)}	_{255ms (± 0.57%)}	_~	_251ms	_265ms	_{p=0.147 n=20}
_{Req 3 - references}	_{28ms (± 2.88%)}	_{25ms (± 3.92%)}	_{🟩-3ms (-10.87%)}	_22ms	_28ms	_{p=0.000 n=20}
_{Req 4 - navto}	_{12ms (± 2.77%)}	_{12ms (± 3.29%)}	_~	_11ms	_14ms	_{p=0.089 n=20}
_{Req 5 - completionInfo count}	_1,363	_1,363	_~	_~	_~	_{p=1.000 n=20}
_{Req 5 - completionInfo}	_{8ms (± 8.12%)}	_{8ms (±11.19%)}	_~	_7ms	_13ms	_{p=0.106 n=20}
_{xstate-main-1-LSP - native}
_{⚠️ Failed}	_failed	_failed

System info unknown

Hosts

native

Scenarios

CompilerLSP - native
Compiler-UnionsLSP - native
xstate-main-1-LSP - native

_Benchmark	_Name	_Iterations
_Current	_pr	₂₀
_Baseline	_baseline	₂₀

startup

Comparison Report - baseline..pr

_Metric	_baseline	_pr
_{lsp-startup - native}
_{⚠️ Failed}	_failed	_failed
_{tsgo-startup - native}
_{⚠️ Failed}	_failed	_failed

System info unknown

Hosts

native

Scenarios

lsp-startup - native
tsgo-startup - native

_Benchmark	_Name	_Iterations
_Current	_pr	₂₀
_Baseline	_baseline	₂₀

Developer Information:

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Reuse token lookup visitor across AST descent

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typescript-automation Bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Oct 22, 2026

Tom S (Tom4ikss) marked this pull request as ready for review October 22, 2026 20:18

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Native token lookup allocates a visitor on each AST descent step #64929

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typescript-automation Bot added For Backlog Bug PRs that fix a backlog bug and removed For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Oct 26, 2026

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Jake Bailey (jakebailey) added the Domain: Performance Reports of unusually slow behavior label Oct 27, 2026

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Merged via the queue into microsoft:main with commit b59ba46 Oct 29, 2026
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Reuse token lookup visitor across AST descent - #64928

Reuse token lookup visitor across AST descent#64928
Jake Bailey (jakebailey) merged 1 commit into
microsoft:mainfrom
Tom4ikss:reuse-token-lookup-visitor

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