Cubase 8 and 8.5 cpu lagging in el capitan

Hi everyone.

Here is the big problem for me.
I am using cubase 8 & 8.5 in OSX el capitan.
Recenty, I found the problem that my imac is lagging without audio playback in my working time with cubase.
The lagging time is almost 30 minutes.
I can not do anything in this situation.
When only working with cubase, I could find that.
I think cubase is not still compatible with el capitan.
Anyone who do you have this problem?