[plt-scheme] excessive refresh

In DrScheme, navigating through my code causes the entire editor screen 
to refresh in order to redraw the paren highlighting, rather than 
refreshing just the affected regions. When I *insert* parens, it 
actually flashes multiple times. This makes editing a pretty rough 
experience -- yesterday I looked in the mirror after a couple hours' 
hacking and my eyes were bright red. :)

Short of recommending I get outside more, is this situation remediable?

Thanks,
Dave

PS I'm not sure if this is specific to Windows.