Slow execution due to front panel background

Hello, I'm experiencing a issue and I don't know how to solve it, it doesn't make any sense for me. In my project I want to use a background image for the front panel (I choosed the metal brushed from LabVIEW). The problem is that with the background the execution is incredibly slow (I measured about 10% more CPU compsumition just because the background).

Any ideas why? I'm using LV2011

Thanks