I've been scratching my head over this for hours now and still can't pinpoint where the problem is coming from.
Basically, the desktop environment takes ages to load on startup and anything which has to do with Mate (panels, application menu, contextual menu, etc...) is slow and laggy (to a crawl). What I don't get is what could possibly have caused this.
The problem literally popped out of nowhere, and after trying to narrow it down, I noticed it comes from the user profile or something in /Home.
With /root being on btrfs, I reverted to an earlier snapshot in an attempt to fix this, but the problem clearly didn't come from the system as it was still existent after the rollback.
This left me with /home (ext4 file system) to test, so I created a new user and logged in with this user. The problem was gone, Mate lightning quick as expected.
I'm running Ubuntu 16.04 Mate (64 bit). Fully updated. No third party software installed except VMware player. Standard ambiance theme (not tweaked). Running 4.4.0-31-generic kernel. 2015 MSI GT72 Gaming Laptop. Using NVIDIA Drivers as default. Macro window manager, Compton for compositing using the GPU (already tried switching to Compiz or software compositing, but didn't fix the issue).
here is the output of systemd-analyze blame:
Here is the output of top:
Here is the output of lspci -k | grep -EA2 'VGA|3D':
01:00.0 VGA compatible controller: NVIDIA Corporation GM204M [GeForce GTX 970M] (rev a1) Subsystem: Micro-Star International Co., Ltd. [MSI] GM204M [GeForce GTX 970M] Kernel driver in use: nvidia
I'm posting this question because I'm desperate for a solution. Google didn't help, I hope you gents/ladies can.
Thank you for taking the time to read.