Whenever I leave OmniWeb up and start using another program when I try to click back into OmniWeb it starts to colored ball for a few minutes. It only started doing this within the last couple weeks, and I have been using it for almost a year now. What could the problem be, and does anyone know a solution?

[Oblique Strategy]

Have you tried deleting your History files located in User/Library/Application Support/OmniWeb 5 ?

There should be several, and you have to quit OmniWeb and move them all to the trash and empty the trash to see the effect. Restart OmniWeb and see if things are a bit snappier.

Whenever OW starts lagging, it's often due to something wrong with the History files - at least in my experience.

[JKT]

See this thread. There is a known issue in the version of WebKit that OmniWeb 5.5.x is based on that can cause hangs and excessive CPU usage by the app. You might be suffering from it.