This is a solution posted on the DirectX archives, its a busy loop to stop dx from rendering ahead.
I dont know if sleeping would be better... but I think this is guaranteed to fix it. The problem is when Flip doesn't halt, the GPU is rendering a backlog of frames while the CPU is blazing ahead. This will force it to halt without locking anything. If Mark or Simon (or anyone else) could port this to BlitzMax (I tried but I dont know which is the frontbuffer in the d3d7 structure) I can give it to some people who were having mouselag problems with my game. A fix would be awesome for this, my game loses like 1/3 of its speed to locking and unlocking.
while( DDERR_WASSTILLDRAWING==FrontBuffer->GetBltStatus(DDGBS_ISBLTDONE) > );
I dont know if sleeping would be better... but I think this is guaranteed to fix it. The problem is when Flip doesn't halt, the GPU is rendering a backlog of frames while the CPU is blazing ahead. This will force it to halt without locking anything. If Mark or Simon (or anyone else) could port this to BlitzMax (I tried but I dont know which is the frontbuffer in the d3d7 structure) I can give it to some people who were having mouselag problems with my game. A fix would be awesome for this, my game loses like 1/3 of its speed to locking and unlocking.