That's your problem right there, "Updated my mac to the latest update." You should be skeptical of Apple product updates unless they regard the security of your device or cover serious issues that you are currently experiencing.
This happened to me and it may or may not apply to you.
I am using a mid 2011 13 inch MBP. I've always updated my OS over the years just as a way to get updates on certain apps here and there. Not once did I ever question it until recently. A few months after Sierra had launched I decided, "Welp why not. It's been a while since I updated my OS." It was at this point that I began to notice FPS drops in League. At first it was just the occasional drop to 10-15 FPS. After updating to High Sierra that's when things kicked in. I went from 45-60 FPS to 15-30 FPS and eventually 0-5 FPS and could not for the life of me figure out why. Naturally I turned on the Activity Monitor app to see what was going on. Nothing out of the ordinary. I start scrolling down. I start noticing that there are a lot of apps running that shouldn't be. Even if it's very little CPU usage when it's a whole lot of them at once it starts to take its toll. Even then they could have been feeding false numbers. I tried force quitting some of them. To my surprise after they closed and stopped they would start right back up. I thought, "Okay... I'll just delete this app if it won't stop running invisibly." This is when the magic happens. "This application cannot be deleted because it is required by the OS." Instantly found out why I had been struggling to run League. I don't have a fancy-shmancy setup but even then shouldn't have trouble running League on the lowest quality possible. Needless to say I factory reseted my PC a few months later because I got fed up with the new OS. Have not experienced anymore FPS issues since then.
If you use Time Machine to back-up your system I'd suggest you restore a version of your system prior to updating your OS to see if you still experience FPS issues or not. If you don't then back-up any important data you have and factory reset your PC.