Framedrop is likely caused by rendering primitives. There's a lot of code in UI that renders without VBOs. GL 3.3 engine can't use CPU-side memory, so it has to upload everything to GPU memory. I implemented a trick that works really good on modern hardware. I don't know what's the exact problem on AMD card but this is likely related to that.
It kinda sucks for AMD, they could easily be a fair competitor for Nvidia if not for the fact that most programs are made for Nvidia cards and therefore have worse performance on AMD cards
IMHO it's something related by Nvidia drivers specific for this GPU (family?) handling opengl2.1 code, as I've checked it both on Radeon and Intel HD and problem with framedrops doesn't occur. Also no one else with different GeForce GPU reported framedrops on this engine, so it's probably issue only on some specific cards.
Well, yep. But I believe it's common problem with OGL 2.1 implementation.As long as main OGL 1.4 have no problems with this GPU, I'm ok with this Nvidia and it's awesome. CUDA's awesome too. And the rest of my games are working great.