game freezes when alt tabbing and using shop, even while using borderless/windowed

after patch 9.12 my game has gotten almost unplayable, usually id recall, buy my items and tp to lane before my hp and mana are even fully restored, but now whenever i open the shop my game freezes for 5-10seconds, one time it even lasted a solid minute, it freezes for the same amount of time when i buy an item, undo what i bought or sell an item. same thing happens when i alt tab, i alt tab instantly, but when tabbing back the game freezes for a few seconds and for a split second my fps counter shows "01 fps" ive tried changing my settings, but it doesnt change anything.

edit: ive actually nearly lost games because any lead i get goes away because i spend a minute in base