It has been circulating on the internet for a week now, AMD officially released the latest Catalyst beta.

AMD recommends using this beta driver for TW3 and Project Cars, and should provide a 10% performance gain with R9 and R7 cards. Visit the download page for more info.

They sure took their time but a 10% performance boost should be worth the wait.

Haven't really noticed much difference playing with my HD7870 but I wasn't expecting much. Well that's a bit of a lie, my pc sounds louder than before. Will play with my setting some today to see if I can change that coz its not nice when ur pc sounds like a hovercraft :)

Not sure what magic they did my performance boost with 7970 is Huge!
Went from 12fps in 4k to 26 and playing in 1440 seem fairly stable around 50fps, on low settings of course.

Pls remember when install driver first remove it through safemode with DDU(from guru3D) this way you have absolute clean install and will not hve errors because still old parts driver on your PC because there all gone. Read instructions its easy in use can be used both for AMD/Nvidia.

Haven't tried them yet, as then I'll have to re-tune my work software that is quite capricious thing, but according to my friend, he noticed exactly no difference in terms of performance, and main crossfire issue - flickering, is still there.
Anyone can confirm?

Actually those days are long past, nowadays you don't even need to reboot. Just install the driver and let it replace the old one, you'll notice the screen go blank then all done.
There are no more "old parts" left behind so don't waste your time trying to uninstall or going into safe mode.

Source : http://www.howtogeek.com/171816/htg-explains-do-you-need-to-use-a-driver-cleaner-when-upgrading-hardware-drivers/

I'd recommend any AMD user install these beta drivers since you're sure to get a performance increase, I know i did.

I'm running intel core i7 4820k with 16gigs ram and a radeon R9 290x 1600x900 rez. I was getting solid 57fps before with drivers 15.4 with all settings uber without hairworks. With hairworks I had 30fps. This is with patch1.04.

With ati drivers 15.5 I'm getting solid 60fps without hairworks and with hairworks still 30fps but more smoother when there is alot of flowing hair or fur around visually.

I don't use hairworks I still see it stressing sometimes. I prefer to make a custom 3d application settings with tessellation. I've overrided application settings and put maximum tessellation level to 16x. Its decent look for the flowing hair.

I did not record much difference with bandicam when playing from AMD pilot 15.3 to 15.5.
It's at worse a drop of 2-3 fps (may be because it's within normal fluctuation).
My guess is that even 10% gain is only 5 fps on a 50 fps scene !
Config : i3, HD 7850, 16 Go RAM.

Could maybe be your cpu holding things back? Don't think so as i3 is pretty close to i5 in most cases but might be worth to take a look at cpu usage just to be sure.

Not sure; i haven't ran around much so could be just demanding environment where i am atm in witcher 3, but performance gain from these drivers seems quite minimal (maybe 1-3fps; not really noticeable). Might be that i have just turned off those settings manually that would see real gains. R9 290 (oc @ 1080mhz) and 1440p monitor.
Cpu is i7 3770k @ 4,3Ghz so it should not be holding back (in witcher 3 highest usage on any single thread i have seen is around 70%)

Same for me on a R9 290X, zero performance gain on 1440p, instead I got some weird random high-pitched fan noise as a bonus. Thanks AMD.

While I agree that installing new drivers without uninstalling old ones should work properly in this day and age, there WILL be "useless scrap" left behind. On my current PC, I had drivers for a GTX 760, HD 7870 and R9 290, all of which were uninstalled with their respective tools (Catalyst / NVidia Experience).

A couple months ago, I decided to do a clean uninstall of old drivers prior to installing those for my new R9 285 and managed to save ~7 GB of memory. So old drivers do in fact leave unneeded scrap. Not function-wise, but storage-wise.

It's called "AMD Radeon™ The Witcher 3 – Wild Hunt beta driver" for a reason.

It's more relevant to dual GPU users(updated crossfire profile). Moreover directly from AMD download site:

"The Witcher 3 - Wild Hunt : Up to 10% performance increase on single GPU Radeon R9 and R7 Series graphics products"

"The Witcher 3 - Wild Hunt : To enable the best performance and experience in Crossfire, users must disable Anti-Aliasing from the games video-post processing options. Some random flickering may occur when using Crossfire. If the issue is affecting the game experience, as a work around we suggest disabling Crossfire while we continue to work with CD Projekt Red to resolve this issue"

Those who runs the game without severe performance issues might be better off waiting for stable release.
I have HD7850 2GB and it seems it has enough power to run game on ultra settings. It's low ram and slow HDD that causes stuttering and long loading times...