Uhm, I get 0.5% spent in rapidFire.check, even though I could imagine some problem may actually happen since lots of mouseover events are generated automatically (in facts, 3.2% of the time is spent in onMouseOver@openseadragon.js:2781).
Notice I'm testing on Nightly (24), so either you've got some other add-on interfering (did you try on a clean profile) or Mozilla fixed (or introduced?) some event dispatch bug in the meanwhile.
Notice I'm testing on Nightly (24), so either you've got some other add-on interfering (did you try on a clean profile) or Mozilla fixed (or introduced?) some event dispatch bug in the meanwhile.