Skilleffects barely loading (since 3.26)

since last league i am expiriencing hard times as alot skills take forever to load, or dont load at all.
alot Boss battles are with 50%+ graphics missing (like ground effects, fire walls and such)

tried cleaning cache, playing around with settings etc.
so far i havent found anything that helps

would be nice to hear from you guys about whats going on here. doing the Quest related bosses alone is quite a pain if u doint know what they are doing >.>