Can You Please Fix the Mac Performance Issues

I play on my imac (leave the haitmail out of this PC users) and since 6.6 there have sever performance issues involving frame rate drops and spikes. The problem is manageable by turning off the sound, but removing sound has a major effect on game-play and enjoyment. I started playing LoL back in season two, but performance problems and the mac beta client being disabled for long periods caused me to stop for years. I've picked the game back up on encouragement from friends and began to really enjoy it again. Once again it feels like Riot doesn't care for a whole demographic of users. I have a Mac because I was an art student and I can't afford to buy a separate PC just to play games on...maybe because I was an art student, but that's neither here nor there. Please, Riot, even if you don't pull Mac out of beta at least put some attention and effort into dealing with these issues so I don't have to stop playing one of the games I enjoy the most and one of the only ones I can regularly play with my friends across the country.