(In reply to Michel Dänzer from comment #21)
> Created attachment 125838 [details] [review]
> loader/dri3: Always use 3 back buffers when flipping
> 
> Does this Mesa patch help?

Yes! With attachment 125838 [details] [review] applied on top of Mesa master 607ab6d3bf I'm seeing
the same performance on 4.7.1 as on 4.6.4.
You can have my
 Tested-by: Kai Wasserbäch <kai@dev.carbon-project.org>

The full stack used (Debian testing as a base) was:
GPU: Hawaii PRO [Radeon R9 290] (ChipID = 0x67b1)
Mesa: Git:master/3fb4a9b3b3 / Git:master/607ab6d3bf + attachment 125838 [details] [review]
libdrm: 2.4.70-1
LLVM: SVN:trunk/r278555 (4.0 devel)
X.Org: 2:1.18.4-1
Linux: 4.7.1
Firmware: Git:master/c170c8d957 (placed in /lib/firmware/updates; fallback
would be firmware-amd-graphics/20160110-1)
libclc: Git:master/785bfd3719
DDX: 1:7.7.0-1