[CRASH] 1-2 Second Game Freeze on death, if Karthus in game, freezes for 30s-2mins (Mac)

I've seen this posted several time throughout the last few months for the Mac version of LoL, but I think can narrow it down a bit. The 1-2second lag on death isn't a huge problem, but I've noticed when KARTHUS is in game, the game goes absolutely nuts with near constant freezes. I have experienced the same symptoms that others have, such as mouse point is still ACTIVE and moveable while the game screen is frozen (If i click on the map while frozen I end up to where I click when it eventually unfreezes). Tabbing out is extremely delayed, 10-30 seconds, only to see beachball spinning until the game unfreezes. It also tends to start to happen after the first death of the game. When the game unfreezes, game notifications/announcements of deaths and kills is substantially behind what is occurring in game. One out of 10 of the freezes the game just up and dies and I have to restart the game and the whole episode to starts over.

This happened in both 10.10.3 and 10.9 running on iMac 3.2Hz NVIDIA GeForce 755m