If you are seeing a performance issue on a benchmark in CrossFire with the latest drivers installed (13.8Beta), we would recommend ensuring that you have done a clean install of your drivers (just to make sure that everything's clear there, check the Sticky for steps on how to do it). If the issues remain, you can raise this as a driver bug at www.amd.com/betareport so that the driver team can investigate it further.
AMD Customer Care
The information presented in this document is for informational purposes only and may contain technical inaccuracies, omissions and typographical errors. Links to third party sites are for convenience only, and no endorsement is implied.