Mac client seriously screwed up

Ever since the release of the new Summoner's Rift, I get nothing but lag, FPS issues, disconnects, and now more commonly, full client crashes. I'm on a 2010 iMac with a great processor and RAM, and I have 15 MBPS internet with usually less than 90-100 ping. However, I don't think I've played a game in the last week and a half that didn't have some sort of problem. Please fix this ASAP. It makes the game completely unplayable, and I'm not going to be punished by LeaverBuster because the client crashed. That's Riot's fault, not mine.