Hi Jayne, I've found that the 'Negative plane islands' DRC check can significantly impact on the speed of the design. You could try disabling this check, and see if there's an increase in performance..... Don't forget to turn it back on!! Cheers, Ben >>> Jayne.Sawyer@xxxxxxxxxxx 20/05/2005 9:34:04 a.m. >>> Since moving to 15.2 and positive planes we have been experiencing considerable lag time when running DRC, using the electrical constraints for diff pairs or doing edits to the planes. The boards we are having issue with are 17" X 14"16 layers23477 connects24000 viaWe are looking to upgrading our hardware. I am hoping that some one in the group might be working with similar conditions and already have updated to a machine that could handle it. If any one can help me to spec a capable machine please let me know.Thanks in advance,Jayne Sawyer NOTICE: This message contains privileged and confidential information intended only for the use of the addressee named above. If you are not the intended recipient of this message you are hereby notified that you must not disseminate, copy or take any action in reliance on it. If you have received this message in error please notify Allied Telesyn Research Ltd immediately. Any views expressed in this message are those of the individual sender, except where the sender has the authority to issue and specifically states them to be the views of Allied Telesyn Research.