Why SLDWORKS.exe switch to " Below Normal" when start Rendering to file?

Anybody notice that SLDWORKS.exe switch to " Below Normal"priority automatically when start Rendering to file?
This symptom was observed since SW2008, maybe SW2007 does the same?

I just don't understand why SLDWORKS.exe doesn't maintain the"Normal " priority as during modeling?

I did not obverse the priority change to "Below Norma" for otherprocess like Simulations.

So every time I have to manually switch it back to Normal or Abovenormal as I believe That will make thing done faster....SolidworksPhotoworks