Comment # 20 on bug 97879 from Eero Tamminen

Apitrace's own CPU overhead is so high that it's not very good for identifying
CPU bottlenecks.

Best would be to do (e.g. from SSH console):
  # perf record -a
  ^C

During the game freeze.

And provide profile report here:
  # perf report

(+ install debug symbols for anything that misses symbols in the report.)