Stutters when using full screen PSEUDO mode

[Hippo123]

Title says it all really, in full screen mode the game runs perfectly. If I run in pseudo full-screen I get very noticeable stuttering (every few seconds or so), especially when turning. Just wondering if anyone knew if it's possible to eliminate this stuttering?

And before anyone suggests "well just run in full screen then", the reason I want to run in pseudo is that it allows me to display other stuff on my second monitor.

Thanks for any replies.