Avoid allocations and no-op work during type inference by jakebailey · Pull Request #65036 · microsoft/TypeScript

Jake Bailey (jakebailey) · 2026-10-29T20:58:05Z

Thanks Steven (@teamchong) for finding these!

Inferring to a target that cannot contain type variables is a no-op: inferFromTypes bails out immediately. Several callers nevertheless did all the work of producing the source side of such a pair before discovering this, e.g. resolving the source parameter or property type, or the source signatures and index infos. Check the target first in applyToParameterTypes, applyToReturnTypes, and inferFromProperties, and only compute the source type when the target could receive inferences. Likewise, look up target signatures and index infos before the source's, and stop early when there are none, since nothing would be inferred from the source anyway. Co-authored-by: Steven Chong <25894545+teamchong@users.noreply.github.com>

When a higher priority inference is made for a type parameter, its existing candidates are discarded. Setting the slices to nil threw away their backing arrays, so the following appends had to allocate and grow new ones from scratch. Truncate the slices instead so the existing capacity is reused. The old elements are cleared first so the discarded candidate types are not kept alive by the backing array. Candidate slices are never shared between inference infos (clones copy them), so reusing them in place is safe. Co-authored-by: Steven Chong <25894545+teamchong@users.noreply.github.com>

Several inference helpers build small temporary slices that never outlive the call: the matched sources and targets in inferFromMatchingTypes, the single-element source list, matched flags, and unmatched sources in inferToMultipleTypes, and the true/false branch pair in inferToConditionalType. These run for nearly every union and conditional type inference, and each one cost a heap allocation. Back these slices with small fixed-size arrays so the common cases stay on the stack, falling back to the heap only when they grow past the buffer. Co-authored-by: Steven Chong <25894545+teamchong@users.noreply.github.com>

Copilot

🟢 Approval recommended

There are no active review issues for the type-inference optimizations.

No open issues 🎉

What changed in this PR

This PR reduces allocation overhead and unnecessary work in the native TypeScript compiler’s type inference.

Changes:

Reuses candidate slice capacity and adds fixed-size buffers for temporary collections.
Skips selected inference work when target types cannot contain type variables.
Returns early when targets have no relevant signatures or index information.

File	Description
`tsc/internal/checker/inference.go`	Optimizes temporary storage and avoids unnecessary type resolution and inference calls.

_{Review effort: Balanced}

Copilot · 2026-10-29T21:02:33Z

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Jake Bailey (jakebailey) · 2026-10-29T21:10:56Z

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

typescript-automation · 2026-10-29T21:11:01Z

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

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

typescript-automation · 2026-10-29T22:19:32Z

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	_88,493	_{+27 (+ 0.03%)}	_~	_~	_{p=0.000 n=20}
_Types	_79,607	_79,607	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{104,122k (± 0.03%)}	_{104,146k (± 0.02%)}	_~	_104,044k	_104,221k	_{p=0.129 n=20}
_{Memory Allocs}	_{1,263,804 (± 0.01%)}	_{1,261,579 (± 0.01%)}	_{-2,224 (- 0.18%)}	_1,261,186	_1,262,066	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.024s (± 6.46%)}	_{0.023s (± 2.28%)}	_~	_0.020s	_0.025s	_{p=0.636 n=20}
_{Bind Time}	_{0.009s (± 5.21%)}	_{0.009s (± 5.86%)}	_~	_0.007s	_0.011s	_{p=0.864 n=20}
_{Check Time}	_{0.216s (± 0.82%)}	_{0.218s (± 2.26%)}	_~	_0.210s	_0.254s	_{p=0.835 n=20}
_{Emit Time}	_{0.143s (± 3.25%)}	_{0.144s (± 3.04%)}	_~	_0.136s	_0.175s	_{p=0.514 n=20}
_{Total Time}	_{0.395s (± 1.14%)}	_{0.397s (± 1.98%)}	_~	_0.385s	_0.437s	_{p=0.523 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_{586,561 (± 0.02%)}	_{585,902 (± 0.01%)}	_{-659 (- 0.11%)}	_585,483	_586,148	_{p=0.000 n=20}
_Types	_{241,687 (± 0.00%)}	_{240,364 (± 0.00%)}	_{-1,323 (- 0.55%)}	_240,360	_240,377	_{p=0.000 n=20}
_{Memory Used}	_{517,857k (± 0.02%)}	_{517,340k (± 0.02%)}	_{-518k (- 0.10%)}	_516,952k	_517,715k	_{p=0.000 n=20}
_{Memory Allocs}	_{7,797,179 (± 0.10%)}	_{7,798,480 (± 0.13%)}	_~	_7,782,544	_7,852,067	_{p=0.414 n=20}
_{Config Time}	_0.009s	_0.009s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.126s (± 2.40%)}	_{0.127s (± 3.25%)}	_~	_0.114s	_0.153s	_{p=0.899 n=20}
_{Bind Time}	_{0.041s (± 5.01%)}	_{0.043s (±10.82%)}	_~	_0.037s	_0.073s	_{p=0.848 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.842s (± 0.92%)}	_{0.844s (± 1.15%)}	_~	_0.817s	_0.894s	_{p=0.909 n=20}
_{Total Time}	_{1.029s (± 1.07%)}	_{1.033s (± 1.37%)}	_~	_0.998s	_1.105s	_{p=0.794 n=20}
_{arktype - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_685,920	_685,049	_{-871 (- 0.13%)}	_~	_~	_{p=0.000 n=20}
_Types	_939,467	_937,452	_{-2,015 (- 0.21%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{497,271k (± 0.01%)}	_{496,581k (± 0.01%)}	_{-690k (- 0.14%)}	_496,289k	_496,768k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,108,430 (± 0.01%)}	_{12,097,533 (± 0.01%)}	_{-10,896 (- 0.09%)}	_12,093,662	_12,105,270	_{p=0.000 n=20}
_{Config Time}	_{0.001s (± 9.93%)}	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.045s (± 5.61%)}	_{0.042s (± 4.35%)}	_{🟩-0.004s (- 8.08%)}	_0.034s	_0.052s	_{p=0.009 n=20}
_{Bind Time}	_{0.013s (± 9.16%)}	_{0.014s (±10.15%)}	_~	_0.011s	_0.021s	_{p=0.332 n=20}
_{Check Time}	_{1.011s (± 1.39%)}	_{1.019s (± 1.63%)}	_~	_0.972s	_1.085s	_{p=0.606 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.099s (± 1.33%)}	_{1.105s (± 1.56%)}	_~	_1.063s	_1.175s	_{p=0.941 n=20}
_{class-transformer - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_45,376	_45,375	_{-1 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_Types	_7,573	_7,571	_{-2 (- 0.03%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{27,832k (± 0.02%)}	_{27,835k (± 0.02%)}	_~	_27,817k	_27,869k	_{p=0.644 n=20}
_{Memory Allocs}	_{248,695 (± 0.06%)}	_{248,602 (± 0.05%)}	_~	_248,140	_249,495	_{p=0.314 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.011s (± 5.21%)}	_{0.012s (± 3.60%)}	_~	_0.009s	_0.013s	_{p=0.845 n=20}
_{Bind Time}	_{0.003s (± 9.34%)}	_{0.004s (±12.61%)}	_~	_0.003s	_0.006s	_{p=0.820 n=20}
_{Check Time}	_{0.009s (± 5.15%)}	_{0.008s (± 5.46%)}	_~	_0.007s	_0.010s	_{p=0.342 n=20}
_{Emit Time}	_{0.009s (± 5.15%)}	_{0.009s (± 6.37%)}	_~	_0.007s	_0.011s	_{p=0.893 n=20}
_{Total Time}	_{0.033s (± 2.54%)}	_{0.033s (± 2.32%)}	_~	_0.028s	_0.035s	_{p=0.941 n=20}
_{effect - native}
_Errors	₁₂	₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,235,115	_1,232,218	_{-2,897 (- 0.23%)}	_~	_~	_{p=0.000 n=20}
_Types	_894,113	_889,284	_{-4,829 (- 0.54%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{940,696k (± 0.02%)}	_{938,628k (± 0.02%)}	_{-2,068k (- 0.22%)}	_937,967k	_939,396k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,671,793 (± 0.03%)}	_{12,628,482 (± 0.09%)}	_{-43,311 (- 0.34%)}	_12,614,740	_12,727,259	_{p=0.000 n=20}
_{Config Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.146s (± 1.72%)}	_{0.150s (± 3.17%)}	_~	_0.138s	_0.185s	_{p=0.198 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.935s (± 1.15%)}	_{0.921s (± 1.04%)}	_{-0.015s (- 1.56%)}	_0.892s	_0.971s	_{p=0.045 n=20}
_{Emit Time}	_{0.505s (± 1.86%)}	_{0.492s (± 2.02%)}	_{-0.013s (- 2.61%)}	_0.455s	_0.538s	_{p=0.050 n=20}
_{Total Time}	_{1.684s (± 0.68%)}	_{1.663s (± 0.90%)}	_{-0.021s (- 1.26%)}	_1.623s	_1.762s	_{p=0.003 n=20}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_3,784,019	_3,783,622	_{-397 (- 0.01%)}	_~	_~	_{p=0.000 n=20}
_Types	_1,355,974	_1,355,172	_{-802 (- 0.06%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{1,836,835k (± 0.08%)}	_{1,837,025k (± 0.05%)}	_~	_1,833,590k	_1,841,171k	_{p=0.904 n=20}
_{Memory Allocs}	_{26,012,176 (± 0.14%)}	_{26,002,059 (± 0.12%)}	_~	_25,907,321	_26,139,270	_{p=0.659 n=20}
_{Config Time}	_{0.008s (± 2.73%)}	_{0.008s (± 2.10%)}	_~	_0.008s	_0.009s	_{p=0.273 n=20}
_{Parse Time}	_{0.293s (± 2.26%)}	_{0.292s (± 2.33%)}	_~	_0.253s	_0.314s	_{p=0.878 n=20}
_{Bind Time}	_{0.001s (±18.96%)}	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{3.137s (± 1.03%)}	_{3.139s (± 1.22%)}	_~	_3.059s	_3.338s	_{p=0.846 n=20}
_{Emit Time}	_{0.243s (± 1.26%)}	_{0.246s (± 1.55%)}	_~	_0.232s	_0.266s	_{p=0.249 n=20}
_{Total Time}	_{4.180s (± 1.03%)}	_{4.175s (± 1.13%)}	_~	_4.021s	_4.416s	_{p=0.763 n=20}
_{sentry - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,793,245	_4,792,310	_{-935 (- 0.02%)}	_~	_~	_{p=0.000 n=20}
_Types	_2,607,045	_2,605,014	_{-2,031 (- 0.08%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{2,880,957k (± 0.03%)}	_{2,880,256k (± 0.03%)}	_~	_2,876,855k	_2,883,281k	_{p=0.383 n=20}
_{Memory Allocs}	_{75,171,435 (± 0.13%)}	_{75,326,517 (± 0.36%)}	_~	_74,985,704	_77,241,597	_{p=0.529 n=20}
_{Config Time}	_{0.025s (± 0.87%)}	_{0.025s (± 0.94%)}	_~	_0.025s	_0.026s	_{p=0.514 n=20}
_{Parse Time}	_{0.471s (± 4.43%)}	_{0.475s (± 3.65%)}	_~	_0.436s	_0.591s	_{p=0.344 n=20}
_{Bind Time}	_{0.179s (±10.49%)}	_{0.163s (± 9.07%)}	_~	_0.133s	_0.215s	_{p=0.106 n=20}
_{Check Time}	_{6.636s (± 0.52%)}	_{6.665s (± 0.49%)}	_~	_6.556s	_6.772s	_{p=0.251 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.364s (± 0.45%)}	_{7.379s (± 0.38%)}	_~	_7.278s	_7.473s	_{p=0.441 n=20}
_{social-app - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,883,074	_1,882,958	_{-116 (- 0.01%)}	_~	_~	_{p=0.000 n=20}
_Types	_1,158,168	_1,157,746	_{-422 (- 0.04%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{972,449k (± 0.02%)}	_{972,353k (± 0.01%)}	_~	_972,007k	_972,874k	_{p=0.224 n=20}
_{Memory Allocs}	_{13,585,125 (± 0.18%)}	_{13,550,974 (± 0.18%)}	_{-34,151 (- 0.25%)}	_13,488,698	_13,695,332	_{p=0.009 n=20}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.161s (± 2.90%)}	_{0.157s (± 2.01%)}	_~	_0.143s	_0.172s	_{p=0.154 n=20}
_{Bind Time}	_{0.043s (±11.51%)}	_{0.044s (± 9.09%)}	_~	_0.038s	_0.073s	_{p=0.184 n=20}
_{Check Time}	_{1.473s (± 0.51%)}	_{1.471s (± 0.59%)}	_~	_1.431s	_1.511s	_{p=0.899 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.700s (± 0.79%)}	_{1.699s (± 0.55%)}	_~	_1.666s	_1.745s	_{p=0.952 n=20}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,184,972	_1,185,075	_{+103 (+ 0.01%)}	_~	_~	_{p=0.000 n=20}
_Types	_438,963	_438,895	_{-68 (- 0.02%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{1,165,134k (± 0.21%)}	_{1,164,879k (± 0.29%)}	_~	_1,153,857k	_1,182,783k	_{p=0.478 n=20}
_{Memory Allocs}	_{47,669,157 (± 0.11%)}	_{47,586,602 (± 0.10%)}	_~	_47,416,404	_47,752,839	_{p=0.052 n=20}
_{Config Time}	_{0.002s (±13.11%)}	_{0.002s (±10.63%)}	_~	_0.001s	_0.002s	_{p=0.436 n=20}
_{Parse Time}	_{0.140s (± 1.55%)}	_{0.140s (± 1.78%)}	_~	_0.128s	_0.148s	_{p=0.931 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.813s (± 0.34%)}	_{0.809s (± 0.32%)}	_{-0.004s (- 0.47%)}	_0.798s	_0.820s	_{p=0.018 n=20}
_{Emit Time}	_{0.140s (± 1.35%)}	_{0.142s (± 1.31%)}	_~	_0.135s	_0.153s	_{p=0.541 n=20}
_{Total Time}	_{9.416s (± 0.42%)}	_{9.416s (± 0.40%)}	_~	_9.243s	_9.611s	_{p=0.718 n=20}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_263,511	_263,551	_{+40 (+ 0.02%)}	_~	_~	_{p=0.000 n=20}
_Types	_196,116	_196,114	_{-2 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{224,586k (± 0.02%)}	_{224,588k (± 0.02%)}	_~	_224,467k	_224,791k	_{p=0.683 n=20}
_{Memory Allocs}	_{2,401,367 (± 0.02%)}	_{2,395,190 (± 0.01%)}	_{-6,178 (- 0.26%)}	_2,393,864	_2,396,667	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.052s (± 2.47%)}	_{0.050s (± 2.90%)}	_~	_0.043s	_0.055s	_{p=0.124 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.377s (± 0.82%)}	_{0.378s (± 0.82%)}	_~	_0.369s	_0.392s	_{p=0.783 n=20}
_{Emit Time}	_{0.050s (± 4.89%)}	_{0.049s (± 5.08%)}	_~	_0.042s	_0.058s	_{p=0.585 n=20}
_{Total Time}	_{0.507s (± 0.54%)}	_{0.505s (± 0.78%)}	_~	_0.488s	_0.520s	_{p=0.304 n=20}
_{t3code-server - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,350,661	_4,347,001	_{-3,660 (- 0.08%)}	_~	_~	_{p=0.000 n=20}
_Types	_3,040,644	_3,032,644	_{-8,000 (- 0.26%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{2,433,934k (± 0.04%)}	_{2,430,719k (± 0.03%)}	_{-3,215k (- 0.13%)}	_2,429,179k	_2,435,890k	_{p=0.000 n=20}
_{Memory Allocs}	_{37,381,017 (± 0.07%)}	_{37,328,928 (± 0.08%)}	_{-52,090 (- 0.14%)}	_37,241,165	_37,442,970	_{p=0.008 n=20}
_{Config Time}	_0.003s	_0.003s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.263s (± 3.08%)}	_{0.258s (± 1.91%)}	_~	_0.238s	_0.277s	_{p=0.372 n=20}
_{Bind Time}	_{0.088s (± 7.98%)}	_{0.093s (±11.48%)}	_~	_0.074s	_0.148s	_{p=0.804 n=20}
_{Check Time}	_{7.447s (± 1.66%)}	_{7.421s (± 1.51%)}	_~	_7.142s	_7.969s	_{p=0.659 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.812s (± 1.61%)}	_{7.786s (± 1.51%)}	_~	_7.482s	_8.369s	_{p=0.678 n=20}
_{tanstack-router - native}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_571,756	_571,642	_{-114 (- 0.02%)}	_~	_~	_{p=0.000 n=20}
_Types	_397,689	_397,273	_{-416 (- 0.10%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{331,435k (± 0.02%)}	_{331,256k (± 0.01%)}	_{-179k (- 0.05%)}	_331,086k	_331,454k	_{p=0.000 n=20}
_{Memory Allocs}	_{4,391,319 (± 0.13%)}	_{4,387,049 (± 0.13%)}	_~	_4,374,495	_4,410,604	_{p=0.096 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.039s (± 2.78%)}	_{0.039s (± 2.61%)}	_~	_0.035s	_0.043s	_{p=0.284 n=20}
_{Bind Time}	_{0.013s (±10.80%)}	_{0.013s (±10.90%)}	_~	_0.011s	_0.023s	_{p=0.491 n=20}
_{Check Time}	_{0.554s (± 0.66%)}	_{0.554s (± 0.61%)}	_~	_0.542s	_0.574s	_{p=0.732 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.626s (± 0.79%)}	_{0.625s (± 0.65%)}	_~	_0.614s	_0.643s	_{p=0.723 n=20}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_231,616	_231,642	_{+26 (+ 0.01%)}	_~	_~	_{p=0.000 n=20}
_Types	_181,195	_181,184	_{-11 (- 0.01%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{193,516k (± 0.01%)}	_{193,528k (± 0.01%)}	_~	_193,428k	_193,640k	_{p=0.516 n=20}
_{Memory Allocs}	_{1,318,122 (± 0.02%)}	_{1,313,962 (± 0.01%)}	_{-4,160 (- 0.32%)}	_1,313,315	_1,314,705	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.044s (± 2.87%)}	_{0.043s (± 3.52%)}	_~	_0.038s	_0.049s	_{p=0.412 n=20}
_{Bind Time}	_{0.021s (± 4.69%)}	_{0.021s (± 5.18%)}	_~	_0.016s	_0.024s	_{p=0.382 n=20}
_{Check Time}	_{0.297s (± 1.06%)}	_{0.292s (± 1.09%)}	_~	_0.282s	_0.304s	_{p=0.062 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.368s (± 0.88%)}	_{0.363s (± 0.92%)}	_~	_0.347s	_0.376s	_{p=0.053 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,504,980	_7,501,701	_{-3,279 (- 0.04%)}	_~	_~	_{p=0.000 n=20}
_Types	_4,419,852	_4,414,140	_{-5,712 (- 0.13%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{5,215,396k (± 0.02%)}	_{5,213,909k (± 0.01%)}	_{-1,487k (- 0.03%)}	_5,210,134k	_5,216,537k	_{p=0.038 n=20}
_{Memory Allocs}	_{57,132,714 (± 0.03%)}	_{57,112,015 (± 0.02%)}	_{-20,699 (- 0.04%)}	_57,096,452	_57,161,323	_{p=0.006 n=20}
_{Config Time}	_{0.035s (± 0.30%)}	_{0.035s (± 0.65%)}	_~	_0.035s	_0.037s	_{p=0.744 n=20}
_{Parse Time}	_{0.903s (± 1.60%)}	_{0.899s (± 1.47%)}	_~	_0.811s	_0.939s	_{p=0.888 n=20}
_{Bind Time}	_{0.294s (± 1.45%)}	_{0.305s (± 7.45%)}	_~	_0.285s	_0.511s	_{p=0.336 n=20}
_{Check Time}	_{7.098s (± 0.40%)}	_{7.131s (± 0.48%)}	_{+0.033s (+ 0.46%)}	_6.871s	_7.228s	_{p=0.014 n=20}
_{Emit Time}	_{2.692s (± 4.43%)}	_{2.625s (± 3.57%)}	_~	_2.538s	_3.461s	_{p=0.899 n=20}
_{Total Time}	_{11.079s (± 0.92%)}	_{11.050s (± 0.72%)}	_~	_10.944s	_11.742s	_{p=0.616 n=20}
_{webpack - native}
_Errors	₆₁₆	₆₁₆	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_917,188	_916,982	_{-206 (- 0.02%)}	_~	_~	_{p=0.000 n=20}
_Types	_636,859	_636,464	_{-395 (- 0.06%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{693,505k (± 0.01%)}	_{693,361k (± 0.02%)}	_~	_692,893k	_693,801k	_{p=0.055 n=20}
_{Memory Allocs}	_{6,499,364 (± 0.05%)}	_{6,493,404 (± 0.03%)}	_{-5,960 (- 0.09%)}	_6,486,784	_6,505,988	_{p=0.001 n=20}
_{Config Time}	_{0.004s (± 2.58%)}	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.145s (± 2.82%)}	_{0.143s (± 3.25%)}	_~	_0.131s	_0.164s	_{p=0.372 n=20}
_{Bind Time}	_{0.046s (± 7.59%)}	_{0.049s (± 8.58%)}	_~	_0.040s	_0.071s	_{p=0.423 n=20}
_{Check Time}	_{1.165s (± 0.50%)}	_{1.165s (± 0.82%)}	_~	_1.133s	_1.214s	_{p=0.857 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.385s (± 0.58%)}	_{1.386s (± 0.58%)}	_~	_1.359s	_1.413s	_{p=0.763 n=20}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_640,490	_640,398	_{-92 (- 0.01%)}	_~	_~	_{p=0.000 n=20}
_Types	_387,984	_385,539	_{-2,445 (- 0.63%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{350,982k (± 0.03%)}	_{350,403k (± 0.03%)}	_{-579k (- 0.17%)}	_350,124k	_350,983k	_{p=0.000 n=20}
_{Memory Allocs}	_{3,991,764 (± 0.07%)}	_{3,986,892 (± 0.07%)}	_{-4,873 (- 0.12%)}	_3,978,052	_3,998,993	_{p=0.049 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.056s (± 3.25%)}	_{0.057s (± 2.49%)}	_~	_0.052s	_0.064s	_{p=0.384 n=20}
_{Bind Time}	_{0.022s (±11.03%)}	_{0.020s (±11.81%)}	_~	_0.017s	_0.033s	_{p=0.173 n=20}
_{Check Time}	_{0.426s (± 0.79%)}	_{0.423s (± 0.73%)}	_~	_0.413s	_0.437s	_{p=0.193 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.511s (± 0.78%)}	_{0.506s (± 0.79%)}	_~	_0.491s	_0.521s	_{p=0.128 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 12:46

Copilot AI balanced review requested due to automatic review settings October 29, 2026 20:58

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

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

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

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Avoid allocations and no-op work during type inference - #65036

Avoid allocations and no-op work during type inference#65036
Jake Bailey (jakebailey) wants to merge 3 commits into
microsoft:mainfrom
jakebailey:perf/inference-scratch

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