Short version:
I have a laptop. Only play League of Legends with 40fps.
Amd grafik chip update
Then I had 60fps
And now a few days later only 38fps
What's this? Can I fix it?
In addition to the graphics card, your FPS are of course dependent on your ping speed to the server. Check your connection?
Have ping 29ms
Mhh… That should not be it.