I posted to AMD forum but was told here may get better responses since the official AMD support forum is dead...
There's currently bunch of articles on Phoronix about 14.4 performance in Ubuntu 14.04...but HOW??? I can't gem them working at all!

So, I'm using ATI 7850, installed Ubuntu (gnome) 14.04. At first I tried fglrx from "Additional drivers", which sucked. So I reverted back to Xorg drivers, which are awesome. Now that the new versionf of Catalyst is available, I convinced myself to give it a try again. So I downloaded the driver from the AMD website, installed, rebooted, and it sucked again. Surprise!

So my issues are:
  • The top 1/3 of the screen was tearing when moving windows, scrolling, etc. Tried all the settings possible with Tear Free and VSYNC. Currently I have two options: Either I use Tear-free, which removes my top screen tearing BUT the whole desktop is totally laggy and slow. Like moving windows around, resizing, showing Gnome Activities, etc...Or when I disable Tear Free, everything is fast and snappy, just like with the Xorg drivers, but the top of the screen is tearing like hell. This is my personal biggest issue, because the desktop experience is absolutely terrible with fglrx. With open source radeon drivers the desktop is extremely fast and snappy...with fglrx just terrible.
  • I can't get HW acceleration working in SMplayer with fglrx. With open source drivers, I just select VDPAU and works like a charm. Can't get it working with fglrx on any settings.
  • Docky has a weird glitch when set to 3D mode, like it extends the dock panel more as it should, without textures applied. I can't provide screenshots since I'm back to open source drivers and I'm tired of constantly reinstalling them.

So there are my problems. I really would like to use Catalyst drivers, as I play some games and I noticed the performance is much better with Catalyst (tried Portal2, Dota2) and also with Catalyst, my GPU fan speed adjusts dynamically with load. With RadeonSI drivers, the GPU reclocks itself, but fan speeds are constant, which is really annoying when the card is idle.

Any help appreciated!