Profiling

lde run --profile samples your program and prints a flat call profile when it exits:

lde run --profile

The profiler runs inside the isolated runtime and samples only your program. Install, build, and module resolution never appear in the report, and lde’s own execution adds no samples of its own.

The report shows two things:

• A VM state breakdown: JIT compiled, interpreted, C code, GC, and JIT compiler time.
• A hotspot table with the top 20 functions by sample count.

The VM state bars show whether the JIT compiled your hot loops, whether C code dominates, or whether the GC is the bottleneck. The hotspot table names the functions.

Flamegraphs

lde run --flamegraph writes an interactive flamegraph:

lde run --flamegraph

The file is profile.html. It is self-contained — open it in any browser, hover over a frame to see its share, and click a frame to zoom. Use --flamegraph=out.html to write elsewhere.

Profiling scripts

The profiler works for loose scripts too:

lde ./bench.lua --profile

Profiling the test suite

To profile the full test suite from a monorepo root:

lde run --profile --flamegraph -- -C packages/foo test

Limitations

--profile and --flamegraph are not supported with --hot or --watch.