I'm having the most annoying issue on my 4,1 cMP (dual 2.93Ghz, 48GB RAM, ATI 7970 w/3GB from MVC, two 27" ViewSonic screens, 512GB SSD Raid array) I get constant input lag on Safari. In typing in boxes just like this one on MacRumors or a review on Amazon the cursor will stop blinking and my text will stop updating. Then it'll all come spewing out on the screen. It's been happening since 10.10, I'm on 10.10.3 and it's slightly improved actually but still really annoying. Anyone else have anything like this? I don't have it on my MacBook Pro, iMacs at the office or a mac mini (all on varying degrees of 10.10). I didn't have it on Mavericks and have a separate Mavericks install that still doesn't have it, so it seems to be unique to 10.10.x and my cMP.