Linux performance workarounds

Disabled-by-default renderer workarounds for machines where sidebar scrolling, tab layout, or streaming Markdown animations regress. Enable only after a measured problem on the official Linux runtime.

Enable it in linux-features/features.json only for a reproduced regression:

{ "enabled": ["linux-performance-workarounds"] }

These are upstream-bundle patches, not baseline compatibility code. Retest the measured regression and run:

node --test linux-features/linux-performance-workarounds/test.js