Let me explain: some days ago i had a performance problem with my engine. For some reason, all the rendering calls seemed to run extremely slowly (by a factor of 10 or about). Nothing seemed to change after i rebooted or reinstalled the latest drivers.. and i didn't change any major thing in my rendering code. I spent, oh well, about 3 hours ? trying to find the cause of this problem.
Finally i got it: i forgot that i had installed GLtrace (a DLL to record GL calls in a text file) in my app's directory in order to test something, some days before. Once my tests were done, i completely forgot to disable GLtrace. So it was still running and logging everything.. every single GL call! No surprize it became slow!
Yesterday i also fixed a small bug in my planet code. I was implementing planet revolutions (self-rotation around an axis) and forgot that my scene graph is fully hierarchical. When a planet was rotating, it made its moons follow the rotation movement too (not only the translation). In order to fix that, i had to split each planet into a center of mass, and an actual body. The fix was easy to implement.