White theme causing constant 8% processor usage

When Using the white theme for google calendar agenda, the processor usage on my machine is on constant 8%. Using a different theme makes the problem go away. No idea what's causing this, but it is really annoying as I find all the other themes unusable, espacially because i use colored events.

As I remember this is caused by an Internet Explorer bug. With white theme, the images on the UI are inverted with CSS filters so that they are visible, and IE doesn't seem to be able to handle this properly. Using Googler one could create a white theme to make it work. With Google Calendar Agenda it is not so easy, the internal theme system doesn't support changing the images.