I just picked up a r7 265 and noticed its performance isn't great with the new unreal 3 ingine and games. Playing dying light there's lag stutter problems at times. Also in crysis 3 witch isn't unreal there's some lag stutter problems as well. I suspect its the drivers including the latest ones given Amd doesn't have a good history with quality drivers. Please get your drivers optimized for the love of God Amd!
Also make sure they install properly because the catalyst install packages are buggy and cause errors on install at times.