As a player, I can say that I like new and HD effects.
The game itself is really old and new effects are making the game nicer for our eyes.
Probably just set all options down in the Performance section? You'll simply switch off all of the effects and all should be fine with your FPS.
Your answer is still elusive at best. Be precise, what effects specifically.
We also didn't add new general effects since the new dumbed-down mortar effects in 4.87.