FPS drops or low FPS after last patch

I get drops below 50 FPS in teamfights after last patch, and my FPS is overall smaller than before. Usually I would get a stable 60+ FPS in fights with many champions and effects, and more than 130 FPS roaming around the map. Now I get around 70 FPS. What's interesting is that even if I use the lowest settings the FPS is still the same. This makes no sense. Both using the legacy or the new client with the Low Spec Mode on. I even fresh re-installed my Windows 7 and it's still the same. Please fix!