Yeah. glBufferData should work fine in this case. To be honest the Windows OpenGL drivers are the ones at fault here. Instead of reusing the old data store the

Yeah. glBufferData should work fine in this case. To be honest the Windows OpenGL drivers are the ones at fault here. Instead of reusing the old data store they seem to allocate a new one, just what glBufferData does. However the performance improvement for glBufferSubData implemented correctly is not enough to offset the huge amount of code that relies on glBufferSubData to behave like glBufferData. So I can see why a driver developer has opted to this behavior.