Need suggestion from 8 laoshi!

My EB1A based i485 has been pending 9 months, i tried SR, infopass and congressman, nothing worked. USCIS replied that security check is open, USCIS can not finish this in nine months. Do you think i need to sue USCIS for this delay or just wait? The suing will result in longer processing or make USCIS speed up? Please give some advice. Thanks.