WindowServer slowness?

Good day! Every so often (almost always when I attempt to use iCal after a while), iCal will lag tremendously, and then catch up with my inputs. I've noticed that during this time, the resources allocated to the WindowServer spike.

More specifically, ps gives me something like
windowse 70 40.7 -3.2 298152 67532 ?? Ss Tue02AM 167:15.99 /System/Library/Frameworks/ApplicationServices.framework/Frameworks/CoreGraphic s.framework/Resources/WindowServer -daemon

I was wondering whether this represented a problem (since it doesn't seem to happen with any other application) or if there were some way to diagnose it? Or "fix" it?

Or am I just being silly?

Thanks a bunch!