So I was working on my OpenGL engine today and I noticed that if I leave it running for ~a minute and a half I start to experience some significant framerate drops. The first thing I did was make sure that there were no OpenGL allocations every frame. After both a code check and a separate profile application check I verified that I am not calling something like glGenBuffers() or something like that. Then I checked for possible issues with dynamic allocations per-frame. The code executed every frame is relatively large, but it doesn't seem like there are any dynamic allocations in the rendering pipeline. I checked the graph of memory usage and it doesn't even seem like I'm allocating any memory except for a little bit here and there, which I assume is coming from PhysX or OpenAL which are both in the program.
I thought that perhaps my CPU or GPU could be thermal throttling (I'm on a laptop). I ran the program until I experienced performance issues, closed it and immediately ran it again. The performance issues stopped once the application was re-run. What also strikes me as odd is that when I tab-out and tab back in the performance issues stop for a short period of time.
I'm a bit puzzled at what is happening here. I highly doubt it's a driver issue as other games work fine, although I haven't tried it on another computer. I've run some standard time-elapsed CPU profiling to try to figure out where the code was getting slow (I know these are generally unreliable because the GPU operates independently) and it just seems like anywhere that is touched by OpenGL just runs slower after the game is left running. Any ideas to what might be causing this? I've noticed this issue for a while but I've always ignored it thinking it was just something else running on the computer until I did extensive testing now so I don't know what code specifically changed this.