So, I will probably use two keyed histograms, one for slow addons (using the same criteria as AddonWatcher.jsm) and one for CPOW (any CPOW is bad, I guess).
Created attachment 8575394 [details] [diff] [review]
1. Reporting CPOW/missed frames by telemetry
This has been made part of bug 674779.
*** This bug has been marked as a duplicate of bug 674779 ***