I'm using a MacBook pro and everything is fine in my games but two things I've noticed is that on the loading screen the little wheel isn't rotating smoothly and whenever I hit enter to type anything my FPS goes to zero for a few seconds and after I get out of chat the game goes back to normal. I have been playing on this computer for 2 years but it started happening right after I patched.
Hey I'm experiencing the same thing. I am playing on my macbook and it never had an issue. Everything runes smooth and locked on 60fps.
After a few game. It started dropping like 0~13 FPS and it is just unplayable. I even cleaned up my macbook, uninstall LoL and reinstall a FRESH LoL and I'm still having that issue. I hope Riot can fix this soon :(
I am playing on a MacBook also, and am experiencing the same exact problem, as long as i am trying to type something in chat my screen is frozen. Then as soon as i hit enter the message sends and my frames go back to normal. there is no indicator that my frames are dropping in the fps number in the corner of the screen. I have tried changing graphic setting and resolution, but nothing is fixing the issue
Ugh mine started doing this yesterday. Just every time I type, game freezes. Teammates almost reported me for non communication lol (even though I pinged) 
I am also using a Macbook Pro (late 2013)
EDIT: i found that it's not the typing part that causes fps drop, it's because of the mouse not being moved for a period of time. Still no fixes though :/
Having a similar issue, fps drops throughout the game but most noticeably when trying to type or while being dead. Also on a Macbook pro, however the issues for me occurred after I updated to the latest OS X 10.12.4. Would be nice to see a red look into this.
Same issue here, running on a MacBook Pro (2013 generation) and since early-mid season 7 have been having massive lag spikes whenever I chat. I've noticed my frames will drop from 60-70 to 1-10 while I type, the screen itself will often freeze. As soon as I hit enter/post my message frames return to normal. Also, during games I have noticed occasional stuttering with loss of frames. This has nothing to do with my internet, and is a recent problem as of the last several months.
I am experiencing the same issue since I updated my mac to sierra 10.12.4...
The problem is not when you open chat, it's when your pointer (mouse) is inactive.
MacBook Pro (Retina, 15-inch, Mid 2015) 2.2 GHz Intel Core i7 16 GB 1600 MHz DDR3 Intel Iris Pro 1536 MB
