Permanent Residents should not have a priority over US citizens.
I am a US citizen. I have filed a Petition for Alien Relative (I-130) for an unmarried daughter over the age of 21 in November 2010. It will take 37.9 months for California Service Center to process this Petition. However, it takes only 29.3 months for processing the same petition filed by a Permanent Resident.
USCIS Processing Time Information for California Service Center:
https://egov.uscis.gov/cris/processingTimesDisplay.do
Please kindly shorten processing time for U.S. citizens, who filed a Petition for Alien Relative (I-130) for an unmarried son or daughter over 21