I noticed that selecting tabs on browsers caused a sluggish changeover. CPU use (on task manager) was normal but there was noticeable delay when selecting menus or tabs. This was on both firefox and chrome but not IE.

The sluggish behaviour went away immediately when displayfusion was exited and came back the minute is was running again. This is on B12. I reinstalled B10 and there is no issue.

Win 8 x64

Workaround:

Settings > Compatibility > Add yourbrowsers.exe > Select 'Disable maximized windows dragging' > OK