STR: - load http://htmlpad.org/debugger.html/ - breakpoint on test - Firefox CPU usage around ~3% - click "click me" - CPU usage slowly (10s) reaches 50% - once not paused anymore (after clicking on resume), CPU usage comes back to normal
Try using the profiler to get some insight into what is happening in that CPU spike. Also, is this on a debug or optimized build?
Hope that helps (profile): http://is.gd/jJes0w
Unfortunately that profile doesn't tell the whole story. We're missing ~83% of the running time of sites called by TA_nest. Perhaps it's OS-specific code that we don't get profiling samples for?
(In reply to Panos Astithas [:past] from comment #3) > Perhaps it's OS-specific code that we don't get profiling samples for? The lack of stack unwinding for native code certainly doesn't help. I'll try with perf after I unbreak my local builds and reboot with a kernel for which i do have perf.
So, this is interesting. While I was able to reproduce with a nightly, I can't reproduce with my local build...
For the record I can't reproduce it on OS X, either or Nightly or on my local build. This must be something Linux-specific.
I can't reproduce with the latest nightly.
So apparently, this has been fixed.