The mobs move so slow

-Running on windows 8.1
-Dell computer
So since the new boost performance update all the mobs in my world stared to lag (the game dosent lag the mobs did) they just walk so slow like 10sec per block, don't know why this happens but it ruins my good times in the 1.8 minecraft , remember this star des to happen wen u started to try to boost fbs in minecraft ,plz fix -love a minecrafter who likes minecraft alot