FPS greatly drop after idle for a while since the last update

Hi, I am having a issue that lol FPS drop after idle for a while. I didn't even launch lol and just let my pc on while I was sleeping, and when I launch LOL again, the client lag and freezing so hard Even I cannot able login because of the freezing https://imgur.com/a/pFIlaCb As you can see in the picture, the login animation FPS seem very laggy and sometimes turn to green screen It goes more worst in game.

In fact, I had reinstalled the game before the last patch because of the same issue. The issue got fixed after the re-installation but it happens again since the last patch

If I restart my pc, it would fix but it would happen again after a long idle. Moreover, this issue doesn't happen on other games such as PUBG

Anyone know how to fix it?

Thank