Startup takes long

[maziac]

Hi, thanks for this very good tool.
I only run into one problem: for me it takes about 10 secs until the benchmarking starts.
(I.e. stepping over "run()" takes 10 seconds, even with "time" set to 100)
So even a single test takes that long.
Is this normal?
Or are there any options to get the time down?

[jerome-benoit]

Hi, the ~10s delay before results is the warmup phase, which is enabled by default. Before the actual measurement, tinybench runs each task through a warmup pass to let the JavaScript engine optimize the code (JIT compilation, inline caches, hidden class stabilization). Without warmup, the first iterations include compilation overhead, which inflates the measured times and reduces result accuracy.

The defaults are:

warmup: true              // enabled by default
warmupTime: 250           // 250ms minimum per task
warmupIterations: 16      // 16 iterations minimum per task

If you have several tasks or your task is slow, warmup alone can account for multiple seconds.

You can reduce it or disable it depending on your needs:

// Faster warmup (still lets the engine optimize, just less)
const bench = new Bench({ time: 100, warmupTime: 50, warmupIterations: 2 })

// No warmup at all (fastest, but first samples may include JIT overhead)
const bench = new Bench({ time: 100, warmup: false })

Disabling warmup is fine for quick iteration during development, but for publishable benchmarks the warmup is recommended to get stable, representative numbers.

[maziac]

With warmup: false I get about 3 secs instead of 11. That's a good improvement. But still quite big.
'time' is set to 100ms. Is it possible to get down to that number?