Unknown problem during game

Hi, this problem started at the beggining of this year, if im not mistaken. During a game, i noticed that when new ally minions or neutral monsters spawns, or even when the enemy champ or minions appear in my field of vision, these "microstops" happens, like if a frame or two gets lost. But it gets worse when I try to do a teamfight (when many champs appear at the same time and attacks at the same time), because then the image stops for almost a second, and it can repeat sometimes in mid teamfights. And that is very problematic, cause I can die without even doing a thing, as if i jump there and stay still for a second. Ive tried many things: Reduced all the video quality settings to the lowest; Adjusted the radeon configurations to improve performance; Included LoL in the avast exception list; Ran troubleshooting and reinstalling LoL; Stopped many other proccess while I play LoL; Updated my graphic, internet and all the other drivers manually;

But none of these changes solved the problem. The game actually runs smooth, around 80 FPS and 50 ms, and ive used speedtest.net and it shows that I have around 71 and 24Mbps download and upload speed respectively, and 13 ms.

I have a laptop with AMD A12 2.5 Ghz, cores 4c+6G, with 12Gb RAM and 512 dedicated graphic memory.

I would really appreciate if someone could help me, cause I tried everything I know X)