The initial roll out of USB mice was on 125Hz polling interval. The PS/2 mice were faster at first because they sent the signal immediately with no delay. You

The initial roll out of USB mice was on 125Hz polling interval. The PS/2 mice were faster at first because they sent the signal immediately with no delay. You can easily see the difference - with 125Hz it's impossible to draw a good circle with a mouse since it will always draw short straight lines