It's probably a lot to do with other stuff and not file size. If I made a game with lots of music and big graphics, it could easily be large while not having much sophistication nor benefit much from these changes.
Complex projects with lots of code -- where the code is the bottleneck for FPS, not the display -- are what would be necessary to benefit. If you're using lots of effects and only a little code, no amount of code optimization would give you a better frame rate. Also whats sets this problem off is lots of objects. I'm working on an NES style game where tiles are 16x16 and everything is super small and barely uses any vram. But I have LOTS of tiles, thus making my relatively small game benefit from these changes.
Now I have no idea what you're working on, but these are just some of the reasons you might now have seen any benefit.