Hello. After upgrading my kernel to 4.14 I noticed strange behavior: If I load
X (KDE 3.5.10 session with built-in compositor [kompmgr], self-compiled with
many patches, X server 1.19.5, nouveau DDX git) and start to use seamonkey 2.49
(again, self-compiled with gtk2 toolkit, not default gtk3) - after some hours
of use X started to eat a lot of CPU time, new windows appear after delay,
glxgears slow down to 11 fps or so from default 60. If I restart X session -
everything back to normal, for few hours. If I quit seamonkey - CPU usage
drops. But if I start it up again - CPU load returns quickly, and not go down
until X restart.

Seamonkey use hw compositing (force-enabled) and multiprocess experimental
option. Problem is, exactly same seamonkey with same set of tabs work fine on
4.12.0 kernel!

I set architecture to ia32, even if kernel compiled for x86_64 , because all my
userspace is 32-bit.

hw:
01:00.0 0300: 10de:0606 (rev a2) (prog-if 00 [VGA controller])
aka
01:00.0 VGA compatible controller: NVIDIA Corporation G92 [GeForce 8800 GS]
(rev a2) (prog-if 00 [VGA controller])

X log, dmesg, opreport data will follow.