Benchmarking advice

Debug Builds

Debug builds (--enable-debug) and non-optimized builds (--disable-optimize) are much slower. Any performance metrics gathered by such builds are largely unrelated to the what the performance a release browser would be.

Poisoning

Many Firefox builds have a diagnostic tool that causes crashes to happen sooner and produce much more actionable information, but also slow down regular usage substantially. In particular, "GC poisoning" is used in all debug builds, and in optimized nightly builds (but not opt developer edition or beta builds). The poisoning can be disabled by setting the environment variable

   JSGC_DISABLE_POISONING=1

before starting the browser.