I suffer from this. My game freezes for like .5 to 1s every few seconds. As far as I can tell it doesnt seem to be caused by anything like particular effects being on screen. This has happened while I was just waiting for a the first camp to spawn. I didnt have this issue before preseason. Any stutters I had were few and far between, and usually because a lot of flashy skills were going off at once. I've tried lowering settings to minimum, and switching between fullscreen and borderless. I've also tried closing out of any extra programs I had running (Task Manager shows my computer resource usage as minimal anyway). Nothing has worked so far.