[Wannabe Mac Megathread] The Last Patch Broke LoL on OS X

Hello fellow Mac players,

I have experienced multiple bugs on Mac since the last patch and looking around the boards, so have a lot of other people. I figured we should make one big thread rather than a hundred small ones to improve visibility.

Chat formatting is completely screwed

1. Clicking on enemy summoner spells breaks the chat. It doesn't show up and then the following messages are all weird. They'll show wrong colours, show the person who clicked on the summoner spell's name as part of the following message, stuff like that. You'll never be able to see enemy summoner spell timers.
2. Pressing Z (or any other key you bound to see expand the chat window) doesn't work in like half the games. It will only show the first few messages that were ever sent and shows less and less messages as more messages get sent.
3. Sometimes (most of the time), messages just straight up don't show up. There is the noise telling you a message was posted, but you can't see it. Occasionally, it will appear later on. Sometimes, you'll never see it.

FPS drops and freezes

1. A lot of people have reported FPS drops, but I have only experienced them twice myself, so I will wait until you guys give me more details to update this section of the post. What happened to me was that my FPS dropped to like 7 mid-way through the games. Both times, I had to close down League and come back to fix it. The problem is, it completely crashed my computer both times so that I had to forcefully reboot it, which cost me about two minutes of the game.
2. My game freezes randomly for a few seconds, especially in the heat of battle.

Crashes Tying in with what I said above, trying to close down the bugged Mac version will often crash your entire computer. I would like someone who has experienced it more often than me to give some details so I can update this section.

Having shitty FPS, freezes and being completely unable to use the chat–a very important tool–properly is quite literally game breaking. This is godawful because this patch is the last patch to play ranked and we're being stripped from the possibility unless Riot puts out a hotfix, which I really hope they do. Is there no bug testing done on Macs? There should be, and this should've been caught. The chat bug happens literally every single game.

I'm personally on OS X El Capitan [10.11.6], playing on a late 2015 iMac with an Intel Iris Pro Graphics 6200 card.

Please leave your bug reports and Mac specs down below, and let's get this thing fixed ASAP.