Speed up node lookup by position, import scanning, and node allocation by jakebailey · Pull Request #65044 · microsoft/TypeScript

Jake Bailey (jakebailey) · 2026-10-29T22:45:06Z

Thanks Steven (@teamchong) for finding these!

@typedef

GetNodeAtPosition descends from the source file by linearly scanning each node's children. At the top level that scan visits every statement in the file, and ForEachDynamicImportOrRequireCall calls GetNodeAtPosition for every textual "import"/"require" match, so files with many statements and many imports did quadratic work. In non-JS files the top-level statements are in source order and do not overlap, so the first statement whose end is past the position can be found by binary search; it is the only candidate that can contain the position. JS files keep the linear scan because reparsed JSDoc statements (@typedef, @import, ...) are inserted ahead of the statement that hosts them and their ranges nest within it. Co-authored-by: Steven Chong <25894545+teamchong@users.noreply.github.com>

ForEachDynamicImportOrRequireCall scanned the source text with strings.IndexAny(text, "ir"), which walks the text byte by byte and stops at every 'i' and 'r' (both very common letters) only to compare and usually reject the keyword there. Search for each keyword with strings.Index instead, which uses the vectorized byte search, and remember the next occurrence of each keyword so it is only searched for again once the scan has passed it. Matches are produced in exactly the same order as before. Co-authored-by: Steven Chong <25894545+teamchong@users.noreply.github.com>

The node factory already allocates the most common node kinds from per-factory arenas, which batches many small heap allocations into a few larger ones and keeps nodes of the same kind close together in memory. A number of other kinds that are created in large numbers when parsing real code and declaration files (imports, object and array literals, arrow functions, methods and properties, binding patterns, template literals, and several type nodes) were still allocated one at a time. Mark 28 more node kinds as arena-allocated so they take the same path. Co-authored-by: Steven Chong <25894545+teamchong@users.noreply.github.com>

Jake Bailey (jakebailey) · 2026-10-29T22:45:17Z

TypeScript Bot (@typescript-bot) perf test this faster

typescript-automation · 2026-10-29T22:45:22Z

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

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

Copilot

🟢 Approval recommended

No active review issues are reported for the AST lookup, import scanning, and node allocation changes.

No open issues 🎉

1 file not reviewed

tsc/internal/ast/ast_generated.go: Generated file

What changed in this PR

This PR targets performance in the native TypeScript compiler by optimizing AST node lookup, import scanning, and node allocation.

Changes:

Use binary search for top-level node lookup in non-JavaScript files, preserving linear traversal for JavaScript.
Cache upcoming import and require matches to avoid repeated searches.
Expand arena allocation to more AST node types through schema and generated factory updates.

File	Description
`tsc/internal/ast/utilities.go`	Optimizes position-based node lookup and import/require scanning.
`tsc/internal/ast/ast_generated.go`	Adds arenas and updates generated constructors to use them.
`tools/scripts/tsc/ast.json`	Enables arena allocation for additional AST node types.

_{Review effort: Balanced}

typescript-automation · 2026-10-29T23:48:55Z

Jake Bailey (@jakebailey)
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}	_{104,137k (± 0.02%)}	_{104,176k (± 0.03%)}	_~	_104,062k	_104,273k	_{p=0.057 n=20}
_{Memory Allocs}	_{1,263,848 (± 0.01%)}	_{1,260,582 (± 0.01%)}	_{-3,266 (- 0.26%)}	_1,260,045	_1,261,072	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.023s (± 2.32%)}	_{0.023s (± 2.19%)}	_~	_0.022s	_0.025s	_{p=0.089 n=20}
_{Bind Time}	_{0.008s (± 4.50%)}	_{0.009s (± 5.19%)}	_~	_0.007s	_0.010s	_{p=0.436 n=20}
_{Check Time}	_{0.212s (± 0.71%)}	_{0.212s (± 0.77%)}	_~	_0.206s	_0.218s	_{p=0.973 n=20}
_{Emit Time}	_{0.139s (± 1.39%)}	_{0.137s (± 0.78%)}	_~	_0.132s	_0.142s	_{p=0.070 n=20}
_{Total Time}	_{0.385s (± 0.65%)}	_{0.384s (± 0.43%)}	_~	_0.377s	_0.391s	_{p=0.671 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_{586,529 (± 0.01%)}	_{586,475 (± 0.02%)}	_~	_586,166	_586,899	_{p=0.380 n=20}
_Types	_{241,687 (± 0.00%)}	_{241,687 (± 0.00%)}	_~	_241,683	_241,699	_{p=0.307 n=20}
_{Memory Used}	_{517,871k (± 0.02%)}	_{519,799k (± 0.02%)}	_{+1,928k (+ 0.37%)}	_519,540k	_520,141k	_{p=0.000 n=20}
_{Memory Allocs}	_{7,809,421 (± 0.20%)}	_{7,636,487 (± 0.13%)}	_{-172,935 (- 2.21%)}	_7,620,984	_7,704,545	_{p=0.000 n=20}
_{Config Time}	_0.009s	_{0.009s (± 1.15%)}	_~	_0.009s	_0.010s	_{p=1.000 n=20}
_{Parse Time}	_{0.129s (± 4.33%)}	_{0.133s (± 5.04%)}	_~	_0.118s	_0.176s	_{p=0.358 n=20}
_{Bind Time}	_{0.046s (± 9.60%)}	_{0.047s (±10.51%)}	_~	_0.038s	_0.068s	_{p=0.791 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.869s (± 1.14%)}	_{0.861s (± 0.98%)}	_~	_0.834s	_0.895s	_{p=0.268 n=20}
_{Total Time}	_{1.065s (± 1.30%)}	_{1.060s (± 1.23%)}	_~	_1.018s	_1.114s	_{p=0.878 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}	_{497,260k (± 0.01%)}	_{497,968k (± 0.01%)}	_{+708k (+ 0.14%)}	_497,737k	_498,199k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,108,644 (± 0.02%)}	_{12,066,760 (± 0.01%)}	_{-41,884 (- 0.35%)}	_12,062,760	_12,072,954	_{p=0.000 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.042s (± 3.82%)}	_{0.043s (± 3.15%)}	_~	_0.037s	_0.050s	_{p=0.307 n=20}
_{Bind Time}	_{0.014s (± 7.45%)}	_{0.014s (± 9.49%)}	_~	_0.011s	_0.021s	_{p=0.973 n=20}
_{Check Time}	_{0.996s (± 1.09%)}	_{0.996s (± 1.01%)}	_~	_0.964s	_1.038s	_{p=0.815 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.082s (± 1.04%)}	_{1.083s (± 0.82%)}	_~	_1.059s	_1.122s	_{p=0.569 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}	_{27,837k (± 0.02%)}	_{27,895k (± 0.02%)}	_{+58k (+ 0.21%)}	_27,872k	_27,933k	_{p=0.000 n=20}
_{Memory Allocs}	_{248,721 (± 0.05%)}	_{241,750 (± 0.06%)}	_{-6,971 (- 2.80%)}	_241,404	_242,794	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.011s (± 3.52%)}	_{0.011s (± 4.13%)}	_~	_0.009s	_0.013s	_{p=0.933 n=20}
_{Bind Time}	_{0.003s (±10.28%)}	_{0.003s (± 7.25%)}	_~	_0.002s	_0.004s	_{p=1.000 n=20}
_{Check Time}	_{0.008s (± 5.50%)}	_{0.009s (±12.58%)}	_~	_0.007s	_0.018s	_{p=0.722 n=20}
_{Emit Time}	_{0.008s (± 6.24%)}	_{0.008s (± 6.77%)}	_~	_0.007s	_0.011s	_{p=0.949 n=20}
_{Total Time}	_{0.032s (± 2.09%)}	_{0.032s (± 3.52%)}	_~	_0.029s	_0.040s	_{p=0.847 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}	_{940,645k (± 0.02%)}	_{942,270k (± 0.02%)}	_{+1,625k (+ 0.17%)}	_941,532k	_943,360k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,670,854 (± 0.02%)}	_{12,536,283 (± 0.05%)}	_{-134,571 (- 1.06%)}	_12,521,638	_12,569,369	_{p=0.000 n=20}
_{Config Time}	_{0.002s (± 5.09%)}	_{0.002s (± 5.09%)}	_~	_0.002s	_0.003s	_{p=1.000 n=20}
_{Parse Time}	_{0.150s (± 0.79%)}	_{0.158s (± 2.89%)}	_{🔻+0.008s (+ 4.98%)}	_0.146s	_0.194s	_{p=0.000 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.951s (± 1.07%)}	_{0.957s (± 1.19%)}	_~	_0.925s	_1.017s	_{p=0.753 n=20}
_{Emit Time}	_{0.512s (± 2.31%)}	_{0.506s (± 2.51%)}	_~	_0.436s	_0.546s	_{p=0.693 n=20}
_{Total Time}	_{1.707s (± 1.09%)}	_{1.716s (± 1.24%)}	_~	_1.638s	_1.804s	_{p=0.365 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}	_{1,836,704k (± 0.07%)}	_{1,840,679k (± 0.07%)}	_{+3,974k (+ 0.22%)}	_1,834,267k	_1,845,628k	_{p=0.000 n=20}
_{Memory Allocs}	_{26,032,286 (± 0.18%)}	_{25,897,765 (± 0.15%)}	_{-134,522 (- 0.52%)}	_25,804,454	_26,121,252	_{p=0.000 n=20}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.291s (± 2.05%)}	_{0.295s (± 2.11%)}	_~	_0.269s	_0.320s	_{p=0.387 n=20}
_{Bind Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{3.087s (± 0.68%)}	_{3.098s (± 0.41%)}	_~	_3.035s	_3.142s	_{p=0.176 n=20}
_{Emit Time}	_{0.241s (± 0.80%)}	_{0.243s (± 2.43%)}	_~	_0.232s	_0.289s	_{p=0.673 n=20}
_{Total Time}	_{4.110s (± 0.52%)}	_{4.127s (± 0.44%)}	_~	_4.051s	_4.214s	_{p=0.151 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	_2,607,045	_2,607,045	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,881,752k (± 0.04%)}	_{2,892,109k (± 0.04%)}	_{+10,357k (+ 0.36%)}	_2,889,014k	_2,896,566k	_{p=0.000 n=20}
_{Memory Allocs}	_{75,274,526 (± 0.38%)}	_{74,751,116 (± 0.25%)}	_{-523,410 (- 0.70%)}	_74,315,643	_75,640,153	_{p=0.000 n=20}
_{Config Time}	_{0.026s (± 1.25%)}	_{0.025s (± 0.57%)}	_{-0.000s (- 1.76%)}	_0.025s	_0.026s	_{p=0.021 n=20}
_{Parse Time}	_{0.476s (± 3.78%)}	_{0.491s (± 3.49%)}	_~	_0.441s	_0.599s	_{p=0.133 n=20}
_{Bind Time}	_{0.166s (±10.73%)}	_{0.165s (± 9.94%)}	_~	_0.135s	_0.238s	_{p=0.722 n=20}
_{Check Time}	_{6.750s (± 0.81%)}	_{6.772s (± 0.51%)}	_~	_6.619s	_6.880s	_{p=0.159 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.470s (± 0.74%)}	_{7.504s (± 0.50%)}	_~	_7.371s	_7.689s	_{p=0.055 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	_1,158,168	_1,158,168	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{972,330k (± 0.02%)}	_{974,994k (± 0.02%)}	_{+2,665k (+ 0.27%)}	_974,192k	_975,782k	_{p=0.000 n=20}
_{Memory Allocs}	_{13,561,583 (± 0.09%)}	_{13,456,507 (± 0.15%)}	_{-105,076 (- 0.77%)}	_13,410,394	_13,585,681	_{p=0.000 n=20}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.158s (± 2.22%)}	_{0.156s (± 1.38%)}	_~	_0.147s	_0.163s	_{p=0.703 n=20}
_{Bind Time}	_{0.044s (± 7.34%)}	_{0.047s (±10.76%)}	_~	_0.039s	_0.071s	_{p=0.984 n=20}
_{Check Time}	_{1.473s (± 0.72%)}	_{1.474s (± 0.57%)}	_~	_1.446s	_1.508s	_{p=0.825 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.702s (± 0.65%)}	_{1.703s (± 0.56%)}	_~	_1.678s	_1.755s	_{p=0.805 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}	_{1,166,748k (± 0.34%)}	_{1,166,668k (± 0.29%)}	_~	_1,155,733k	_1,189,919k	_{p=0.764 n=20}
_{Memory Allocs}	_{47,668,424 (± 0.10%)}	_{47,278,797 (± 0.11%)}	_{-389,627 (- 0.82%)}	_47,094,833	_47,523,042	_{p=0.000 n=20}
_{Config Time}	_{0.002s (±11.84%)}	_{0.002s (± 9.24%)}	_~	_0.001s	_0.002s	_{p=0.695 n=20}
_{Parse Time}	_{0.140s (± 1.87%)}	_{0.139s (± 1.68%)}	_~	_0.127s	_0.146s	_{p=0.722 n=20}
_{Bind Time}	_0.000s	_{0.000s (±208.60%)}	_~	_0.000s	_0.001s	_{p=1.000 n=20}
_{Check Time}	_{0.812s (± 0.47%)}	_{0.811s (± 0.43%)}	_~	_0.794s	_0.825s	_{p=0.643 n=20}
_{Emit Time}	_{0.139s (± 1.02%)}	_{0.139s (± 0.78%)}	_~	_0.134s	_0.143s	_{p=0.803 n=20}
_{Total Time}	_{9.379s (± 0.37%)}	_{9.402s (± 0.40%)}	_~	_9.292s	_9.557s	_{p=0.606 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}	_{224,656k (± 0.02%)}	_{224,748k (± 0.02%)}	_{+92k (+ 0.04%)}	_224,523k	_224,857k	_{p=0.001 n=20}
_{Memory Allocs}	_{2,401,513 (± 0.01%)}	_{2,384,599 (± 0.01%)}	_{-16,914 (- 0.70%)}	_2,383,438	_2,385,966	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.050s (± 3.27%)}	_{0.051s (± 3.84%)}	_~	_0.045s	_0.058s	_{p=0.392 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.396s (± 0.96%)}	_{0.396s (± 0.87%)}	_~	_0.386s	_0.408s	_{p=0.814 n=20}
_{Emit Time}	_{0.048s (± 5.74%)}	_{0.051s (± 5.92%)}	_~	_0.042s	_0.060s	_{p=0.392 n=20}
_{Total Time}	_{0.523s (± 1.05%)}	_{0.528s (± 0.85%)}	_~	_0.513s	_0.550s	_{p=0.151 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	_3,040,644	_3,040,644	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,433,815k (± 0.02%)}	_{2,436,377k (± 0.02%)}	_{+2,562k (+ 0.11%)}	_2,433,901k	_2,438,411k	_{p=0.000 n=20}
_{Memory Allocs}	_{37,365,624 (± 0.06%)}	_{37,126,627 (± 0.07%)}	_{-238,996 (- 0.64%)}	_37,049,903	_37,268,270	_{p=0.000 n=20}
_{Config Time}	_0.003s	_0.003s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.247s (± 1.90%)}	_{0.247s (± 2.20%)}	_~	_0.225s	_0.272s	_{p=0.963 n=20}
_{Bind Time}	_{0.086s (±10.02%)}	_{0.084s (± 7.81%)}	_~	_0.075s	_0.128s	_{p=0.530 n=20}
_{Check Time}	_{7.184s (± 0.46%)}	_{7.211s (± 0.38%)}	_~	_7.116s	_7.321s	_{p=0.090 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.530s (± 0.45%)}	_{7.557s (± 0.34%)}	_~	_7.465s	_7.660s	_{p=0.090 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}	_{331,416k (± 0.01%)}	_{331,803k (± 0.01%)}	_{+387k (+ 0.12%)}	_331,652k	_331,989k	_{p=0.000 n=20}
_{Memory Allocs}	_{4,393,866 (± 0.22%)}	_{4,361,803 (± 0.22%)}	_{-32,063 (- 0.73%)}	_4,346,754	_4,425,772	_{p=0.000 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.041s (± 4.63%)}	_{0.040s (± 4.16%)}	_~	_0.034s	_0.047s	_{p=0.752 n=20}
_{Bind Time}	_{0.013s (±11.57%)}	_{0.013s (±10.67%)}	_~	_0.011s	_0.020s	_{p=0.672 n=20}
_{Check Time}	_{0.554s (± 0.68%)}	_{0.557s (± 0.76%)}	_~	_0.543s	_0.573s	_{p=0.184 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.626s (± 0.71%)}	_{0.630s (± 0.81%)}	_~	_0.613s	_0.651s	_{p=0.261 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}	_{193,542k (± 0.01%)}	_{193,610k (± 0.01%)}	_{+68k (+ 0.03%)}	_193,443k	_193,702k	_{p=0.000 n=20}
_{Memory Allocs}	_{1,318,096 (± 0.01%)}	_{1,304,937 (± 0.02%)}	_{-13,159 (- 1.00%)}	_1,304,373	_1,306,167	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.044s (± 3.35%)}	_{0.045s (± 2.15%)}	_~	_0.041s	_0.049s	_{p=0.143 n=20}
_{Bind Time}	_{0.021s (± 6.14%)}	_{0.021s (± 5.08%)}	_~	_0.018s	_0.026s	_{p=0.390 n=20}
_{Check Time}	_{0.306s (± 0.94%)}	_{0.309s (± 1.25%)}	_~	_0.296s	_0.329s	_{p=0.255 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.377s (± 0.84%)}	_{0.382s (± 1.00%)}	_~	_0.371s	_0.401s	_{p=0.086 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,495,791	_7,495,791	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,391,777	_4,391,777	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{5,196,778k (± 0.01%)}	_{5,208,603k (± 0.02%)}	_{+11,825k (+ 0.23%)}	_5,205,670k	_5,212,374k	_{p=0.000 n=20}
_{Memory Allocs}	_{57,052,522 (± 0.02%)}	_{55,367,853 (± 0.02%)}	_{-1,684,668 (- 2.95%)}	_55,341,271	_55,459,491	_{p=0.000 n=20}
_{Config Time}	_{0.036s (± 1.82%)}	_{0.039s (±16.63%)}	_~	_0.035s	_0.098s	_{p=0.835 n=20}
_{Parse Time}	_{0.920s (± 2.32%)}	_{0.944s (± 2.56%)}	_~	_0.846s	_1.051s	_{p=0.082 n=20}
_{Bind Time}	_{0.311s (± 6.28%)}	_{0.321s (± 7.85%)}	_~	_0.291s	_0.525s	_{p=0.267 n=20}
_{Check Time}	_{7.390s (± 1.78%)}	_{7.407s (± 2.00%)}	_~	_7.032s	_7.980s	_{p=0.525 n=20}
_{Emit Time}	_{2.827s (± 4.81%)}	_{2.880s (± 4.35%)}	_~	_2.631s	_3.497s	_{p=0.234 n=20}
_{Total Time}	_{11.542s (± 1.93%)}	_{11.649s (± 1.80%)}	_~	_11.191s	_12.382s	_{p=0.091 n=20}
_{webpack - native}
_Errors	₆₁₆	₆₁₆	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_923,808	_923,808	_~	_~	_~	_{p=1.000 n=20}
_Types	_649,949	_649,949	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{698,675k (± 0.02%)}	_{699,860k (± 0.01%)}	_{+1,185k (+ 0.17%)}	_699,429k	_700,287k	_{p=0.000 n=20}
_{Memory Allocs}	_{6,572,075 (± 0.06%)}	_{6,450,425 (± 0.05%)}	_{-121,650 (- 1.85%)}	_6,442,854	_6,462,817	_{p=0.000 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.143s (± 3.46%)}	_{0.143s (± 3.10%)}	_~	_0.129s	_0.161s	_{p=0.763 n=20}
_{Bind Time}	_{0.048s (±12.16%)}	_{0.046s (±11.20%)}	_~	_0.039s	_0.077s	_{p=0.497 n=20}
_{Check Time}	_{1.108s (± 1.10%)}	_{1.117s (± 1.29%)}	_~	_1.066s	_1.179s	_{p=0.310 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.327s (± 1.13%)}	_{1.335s (± 1.42%)}	_~	_1.289s	_1.412s	_{p=0.774 n=20}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_640,490	_640,490	_~	_~	_~	_{p=1.000 n=20}
_Types	_387,984	_387,984	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{350,907k (± 0.02%)}	_{351,493k (± 0.02%)}	_{+586k (+ 0.17%)}	_351,296k	_351,909k	_{p=0.000 n=20}
_{Memory Allocs}	_{3,990,220 (± 0.08%)}	_{3,950,728 (± 0.08%)}	_{-39,492 (- 0.99%)}	_3,938,124	_3,965,557	_{p=0.000 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.060s (± 2.92%)}	_{0.060s (± 2.80%)}	_~	_0.053s	_0.067s	_{p=0.941 n=20}
_{Bind Time}	_{0.023s (±11.16%)}	_{0.022s (± 9.65%)}	_~	_0.017s	_0.032s	_{p=0.778 n=20}
_{Check Time}	_{0.416s (± 1.10%)}	_{0.428s (± 4.50%)}	_~	_0.411s	_0.602s	_{p=0.060 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.503s (± 1.05%)}	_{0.517s (± 3.72%)}	_~	_0.494s	_0.689s	_{p=0.058 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

Developer Information:

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Jake Bailey (jakebailey) and others added 3 commits October 29, 2026 14:55

Copilot AI balanced review requested due to automatic review settings October 29, 2026 22:45

github-project-automation Bot added this to PR Backlog Oct 29, 2026

typescript-automation Bot assigned Jake Bailey (jakebailey) Oct 29, 2026

github-project-automation Bot moved this to Not started in PR Backlog Oct 29, 2026

typescript-automation Bot added Author: Team For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Oct 29, 2026

Copilot started reviewing on behalf of Jake Bailey (jakebailey) October 29, 2026 22:45

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Jake Bailey (jakebailey) added the Domain: Performance Reports of unusually slow behavior label Oct 29, 2026

Daniel Rosenwasser (DanielRosenwasser) reviewed Oct 29, 2026

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Comment thread tsc/internal/ast/utilities.go Resolved

Return early from indexFrom at the end of the text

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Speed up node lookup by position, import scanning, and node allocation - #65044

Speed up node lookup by position, import scanning, and node allocation#65044
Jake Bailey (jakebailey) wants to merge 4 commits into
microsoft:mainfrom
jakebailey:perf/parser-ast

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