I'm having the exact same problem, but on a radeon driver. In my case, the problem started after an upgrade I did on December 10th, as shown below:
2016-12-10 10:10:08 upgrade ncurses-bin:amd64 6.0+20160917-1 6.0+20161126-1 2016-12-10 10:10:09 upgrade ncurses-base:all 6.0+20160917-1 6.0+20161126-1 2016-12-10 10:10:12 upgrade libncurses5:amd64 6.0+20160917-1 6.0+20161126-1 2016-12-10 10:10:13 upgrade libtinfo5:amd64 6.0+20160917-1 6.0+20161126-1 2016-12-10 10:10:15 upgrade libncursesw5:amd64 6.0+20160917-1 6.0+20161126-1 2016-12-10 10:10:16 upgrade ncurses-term:all 6.0+20160917-1 6.0+20161126-1 2016-12-10 10:10:18 upgrade libavutil55:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:19 upgrade libswresample2:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:20 upgrade libavcodec57:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:22 upgrade libavformat57:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:22 upgrade libavresample3:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:23 upgrade libpostproc54:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:24 upgrade libswscale4:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:26 upgrade libavfilter6:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:27 upgrade libavdevice57:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:27 upgrade ffmpeg:amd64 7:3.2.1-1 7:3.2.2-1 2016-12-10 10:10:28 upgrade libxfont1:amd64 1:1.5.2-1 1:1.5.2-4 2016-12-10 10:10:29 upgrade xserver-common:all 2:1.18.4-2 2:1.19.0-2 2016-12-10 10:10:30 upgrade xserver-xorg-input-evdev:amd64 1:2.10.4-1 1:2.10.4-1+b1 2016-12-10 10:10:31 upgrade xserver-xorg-video-radeon:amd64 1:7.8.0-1 1:7.8.0-1+b1 2016-12-10 10:10:32 upgrade xserver-xorg-video-ati:amd64 1:7.8.0-1 1:7.8.0-1+b1 2016-12-10 10:10:32 upgrade xserver-xorg-video-mach64:amd64 6.9.5-1+b1 6.9.5-1+b2 2016-12-10 10:10:33 upgrade xserver-xorg-video-tdfx:amd64 1:1.4.6-2 1:1.4.6-2+b1 2016-12-10 10:10:34 upgrade xserver-xorg-video-cirrus:amd64 1:1.5.3-1+b1 1:1.5.3-1+b2 2016-12-10 10:10:34 upgrade xserver-xorg-video-amdgpu:amd64 1.2.0-1 1.2.0-1+b1 2016-12-10 10:10:35 upgrade xserver-xorg-video-dummy:amd64 1:0.3.7-1+b5 1:0.3.7-1+b6 2016-12-10 10:10:36 upgrade xserver-xorg-video-vesa:amd64 1:2.3.4-1+b1 1:2.3.4-1+b2 2016-12-10 10:10:36 upgrade xserver-xorg-video-trident:amd64 1:1.3.7-2 1:1.3.7-2+b1 2016-12-10 10:10:37 upgrade xserver-xorg-video-vmware:amd64 1:13.2.1-1 1:13.2.1-1+b1 2016-12-10 10:10:38 upgrade xserver-xorg-video-neomagic:amd64 1:1.2.9-1+b1 1:1.2.9-1+b2 2016-12-10 10:10:38 upgrade xserver-xorg-video-mga:amd64 1:1.6.4-2 1:1.6.4-2+b1 2016-12-10 10:10:39 upgrade xserver-xorg-video-savage:amd64 1:2.3.8-2 1:2.3.8-2+b1 2016-12-10 10:10:40 upgrade xserver-xorg-video-fbdev:amd64 1:0.4.4-1+b4 1:0.4.4-1+b5 2016-12-10 10:10:40 upgrade xserver-xorg-video-nouveau:amd64 1:1.0.13-1 1:1.0.13-1+b1 2016-12-10 10:10:41 upgrade xserver-xorg-video-qxl:amd64 0.1.4-3+b1 0.1.4+20161126git4d7160c-1 2016-12-10 10:10:42 upgrade xserver-xorg-video-r128:amd64 6.10.1-2 6.10.1-2+b1 2016-12-10 10:10:42 upgrade xserver-xorg-video-intel:amd64 2:2.99.917+git20161105-1 2:2.99.917+git20161105-1+b1 2016-12-10 10:10:44 upgrade xserver-xorg-input-mouse:amd64 1:1.9.2-1 1:1.9.2-1+b1 2016-12-10 10:10:44 upgrade xserver-xorg-input-wacom:amd64 0.33.0-1 0.33.0-1+b1 2016-12-10 10:10:45 upgrade xserver-xorg-input-void:amd64 1:1.4.1-1+b1 1:1.4.1-1+b2 2016-12-10 10:10:46 upgrade xserver-xorg-input-libinput:amd64 0.22.0-1 0.22.0-1+b1 2016-12-10 10:10:46 upgrade xserver-xorg-core:amd64 2:1.18.4-2 2:1.19.0-2 2016-12-10 10:10:48 upgrade xserver-xorg-input-synaptics:amd64 1.9.0-1 1.9.0-1+b1 >From the log above (excerpted from /var/log/dpkg.log), I'm pretty sure the problem came from an xserver-xorg upgrade. I just tried the solution suggested on comment #3 at the link below and haven't seen the problem since then (it's been less than one hour though). http://www.linuxquestions.org/questions/slackware-14/lags-and-freezes-on-ati-rs880-%5Bradeon-hd-4290%5D-with-new-xf86-video-ati-7-8-0-a-4175594206/ Cheers, Adriano
