W3 total cache + adrotate

Hi, i am currently using adrotate with w3 total cache and recently i noticed that when i clear w3 total cache caches, mysql use all cores on server and let the server without response for some seconds.
I use adrotate this way:
home – 3 blocks with group code loading 8 banners in rotate mode
post – 2 blocks with group code loading 13 banners in rotate mode
Before installing adrotate this problem was not happening.
Do you have any advice on how to increase performance on w3 total cache caches clear? Any other cache plugin works well with adrotate? Hosting upgrade actually is not an option.