WowAce

Hey,I am playing a rogue and starting from z-pearl addon version 5.1.3 I have great performance drops when using rogue skill "stealth".I have rather powerful computer(4790k,radeon 290x,16g of ram,ssd) so this isn't a problem of PC.
Talking about steps that cause such a bug:
I am standing in room or place without people to make the test more qualitative(my fps is 115 at that moment)then using stealth and it drops till 75,then it returns to 115 again,after I am going out from stealth in drops again to 75-90 and then it is again 115.Intervals between drops is 1-2 second,you can tell that there is no problem,but it was a calm place in WoW,in raids fps can drop up to 25 and again to 75,so the game starts to be uncomfortable .
I have tested all the versions of addon and could absolutely say that the problem is in version 5.1.3 and newer one ,as in 5.1.2 everything is ok.
Hope it could be fixed =(

Also i could add that I installed WoW from the beginning,using only Z-pearl, and the fps froblems are just with that addon.