I've done a bit of testing with all Pyanodon mods and not seen anything unexpected. But the mod is brand new and might still have undiscovered side effects. Feel free to report anything you find.
The degree of reduction can be set in the mod settings. Defaults are tuned for about 50% reduction while trying to keep visual impact reasonably low. Settings range from no reduction to disabling animations completely.
Compatible with all mods. Yes. Really all of them.
Not everyone has the latest high-end graphics card and large modpacks with lots of new buildings can hit the limits of what a system can comfortably handle. If you're not low on system memory (RAM) or graphics memory (VRAM) then this mod will not improve your framerate.
How does it work? (Technical)
VRAM Saver prodecurally detects animations and replaces some frames with repetitions of the previous frame, so that fewer frames are loaded by the engine. There's some smartness built-in so small working animations or similar are left untouched because they wouldn't save much VRAM anyway. Additionally belts and a few other visually important entities are also left intact to not make the factory too ugly.
Sopel for the idea to save VRAM by disabling all animations.
Kingarthur and kirazy for the idea to use frame sequences for saving VRAM without completely removing animations.
Eradicator for writing all the code.