[badsectoracula]

Yeah i thought about it and you can sync the GPU and CPU (basically wait until the GPU stops doing anything) and even bruteforcing a sync before and after every register change it didn't solve things :-/.

It might still be something i'm doing wrong GPU-wise, but these flickers happen with static geometry (the memory for which is allocated at init) -seemingly- because of "damaged" transformation matrices (modelview and projection) passed to the vertex shader. The matrices are inlined in the push buffer (i.e. become part of it) that contains the commands to setup the render state before the command that draws primitives using them, so basically it is impossible for the GPU to "miss" them :-P.