Aion Riftshade

Whenever i log into game my frames are good and there isnt any lags, but after maybe 10 minutes of playing, the frames drop to 40 and less and stay there, i have good specs and this is the first time it happens, before everything was nice but since the latest ddos attack happened this problem started, is there a fix? 

I have tried to fix the client i also re-installed the game several times and nothing happens