mouselag

There is absolutely no difference between the drivers on my machine:

'SetGraphicsDriver D3D7Max2DDriver()
'SetGraphicsDriver GLMax2DDriver()
'SetGraphicsDriver BufferedD3D7Max2DDriver()
Graphics 640,480,0,0

Repeat
	Cls
	For i = 0 To 100000
		SetColor Rand(55),Rand(55),Rand(55)
		DrawRect Rand(0,640),Rand(0,480),10,10
	Next
	
	'Flip
	
	SetColor 255,255,255
	DrawOval MouseX()-3,MouseY()-3,5,5
	
	Flip
Until KeyHit(KEY_ESCAPE) Or AppTerminate()

So it might be a driver issue, or specific to certain graphics cards?

Try uncommenting the Flip before the mouse drawing to see if that makes a difference for you.