FPS fluctuations makes league unplayable after masOS Mojave 10.14.1 update

I have been playing league on my Mac problem free for about 4 months now. However there was an update to the Mojave update (10.14.1 i believe) and I recall logging on league about a week ago and saw a pop-up message saying something about league won't be able to run properly on this version of macOS but given I was about to start a match I ignored it thinking everything would be fine. I played a couple games that day great but the only issue was that League voice chat wasn't working at all. Now today when trying to play with a friend, it was completely unplayable. The FPS kept spiking literally every second from 0 to 200 to 20 to 160 and so on. I could hardly move and I lowered the resolution and graphics and still nothing. I also reinstalled League but the problem still persisted. I noticed the FPS was fine when in a custom 1v1 but in pvp or co vs ai the problem is there. It seems to me that I won't be able to play league again until perhaps the next update. Hopefully someone can help.