I have recently been running Ubuntu 16.04 LTS with the MATE desktop. So far it seems to be a fast and pretty stable system, but there have been a couple of glitches. The most noticeable is that Firefox disappears from the desktop when maximized when the Compiz window manager is used instead of Marco - software compositor or Marco - Compton. The program shows as minimized in the tray, but when I maximize it, it's invisible. Switching the window manager (which can be done on-the-fly) back to Marco - software / Compton immediately makes the program visible again. Everything else (that I've tried this on) is unaffected by changing the window manager. It's not a deal breaker by any means, especially since I am not at this time trying to run a bunch of fancy 3D effects, but at some point I might want to run all that stuff again...

Another issue I've noticed is that the screensaver will not activate when the Marco - Compton compositor is running. It starts and immediately stops. The monitor still sleeps as does the computer after the specified time. The difference between the software compositor and Compton is not very noticeable under average conditions, but higher frame rates / complex moving images show less tearing with Compton than with the software compositor. I understand that Compton is a direct rendering pass-through which sends graphics instructions directly to the GPU instead of routing them through the X window system. The issue of the screensaver will likely be fixed in a future update.

Something else which I have noticed, which is more of minor annoyance than anything else, is that when AT&T's DNS servers are slow, I see resolution times between 2000 and 4500 msec. I swear this makes me think of satellite Internet! Anyway, I looked to see if DNS caching was installed, and interestingly enough, the dnsmasq-base package is installed but not the higher level configuration options... I always run a local DNS cache, which reduces query times to zero and and significantly speeds up browsing. I had to install the dnsmasq package to get an /etc/dnsmasq.config to be able to get easily settable options. One option that I wanted was to be able to set the cache retention time, which by default in dnsmasq-base is 0 msec, which means that a cache entry, once stored, will be purged after it is used -- I know this is to force lookup frequently, but I seldom if ever see problems with stale DNS data to begin with.

I set the local-ttl option in /etc/dnsmasq.conf to 600 sec, which seems to be a pretty good value so far. Sometimes the AT&T nameservers are fast, sometimes quite slow... if I bring up a terminal and dig google.com, I can get as low as 30 msec and as many as 4500 msec, but once the resolution is cached, if I dig google.com I get 0 msec, which shows the DNS resolution is coming from the local DNS cache. The IP is 127.0.0.1 which is localhost, which is where you want /etc/resolv.conf pointed as the primary nameserver. The AT&T nameserver is secondary. You do NOT need to edit /etc/resolv.conf manually since it will be autoconfigured by your settings in /etc/dnsmasq.conf once you have it set up. In most cases, you'll have little to do as almost everything is set correctly for the typical user. The more complex your network is the more you'll have to set, like forwarding options. The typical user can just install dnsmasq from Synaptic and open /etc/dnsmasq.conf in Pluma or gedit and set a longer retention time if they wish.

DR