Luau Profile tab

System Tools tab for the Luau sampling profiler. Distinct from the existing profiler.module tab — that one renders engine system timings (per-frame, deterministic, named systems via record_timing); this one renders the Luau sampling profiler (luau_profile.*) which is statistical and stack-folded. They complement each other:

• Profiler tab — "what did each Bevy system cost this frame"
• Luau Profile tab — "which Luau functions are hot, and which lines inside them"

Contents

• Start/Stop toggle for the background sampler
• Hz presets (250, 1k, 4k, 10k) — clicking sets currentHz and restarts the sampler at the new rate if running
• Reset clears the accumulator without stopping the sampler
• Dump writes a folded-stack file under /zero/runtime/luau_profile/profile_<ts>.folded (note: the engine resolves this to an actual filesystem path; the underlying luau_profile.dump(path) takes a real fs path)
• Live flamegraph (icicle) via the reusable @builtin::modules.ui.flamegraph widget
• Top stacks list sorted by self-time %
• Regions table — count/total/avg/max for every named luau_profile.region()

Refresh

1 Hz tick driven by the System Tools shell. The snapshot path is in-process (no disk I/O), so per-frame polling is cheap.

See also

• docs/guides/luau-profiling.md — full profiling guide
• @builtin::modules.ui.flamegraph — the reusable flamegraph widget
• @builtin::tools.perf.luau — command-style toolbox surface for one-liner profiling