I've been running the Ubuntu 20.10 for a couple weeks now on my 8Gb RPi 4 with SSD.
Bottom line is I'm very likely going to stick with it.
The good news:
- The VNC connection seems a bit more reliable for Ubuntu--RaspberryPi OS vnc seemed to freeze every now and then. This was usually fixable by disconnecting and re-connecting, but a bit annoying. Sometimes it took a bit more prodding to wake up. For my network, I'm using a pair of powerline adapters and wired ethernet.
- Also, the graphics are much clearer. E.g. the HFR numbers on the full-field focus image were never very readable--I always wondered why people didn't complain about it With Ubuntu, they're perfectly readable. Same resolution, 1920x1080 on both.
The bad news
- The windowing responsiveness is worse (until yesterday, see below).
In fact, the responsiveness was much worse, until yesterday, and I wasn't sure what I was going to do (since I do like the reliability and picture quality). Doing some googling yesterday, I found some posts suggesting removing a desktop background, and going with a solid color background. I had this
California Nebula pic
as my background. I swapped it out for a solid black background, and, sure enough, responsiveness is now about what the RPi4 OS's responsiveness was
(with the CA Neb background). That's not not blindingly fast by any means, but it's workable. I guess that somehow Ubuntu's x11vnc vnc-server is serving up more picture quality at the expense of latency, but I can't seem to find a control to trade it off a little--I tried the obvious quality user setting, set to Auto but tried medium and low, but that did nothing for me.
I guess you could say that RPi OS can handle a background and Ubuntu can't so RPi OS is a bit quicker, and I'd agree with that.
Let me know if you have any further suggestions--I'm running the following to start VNC on Ubuntu:
/usr/bin/x11vnc -auth guess -forever -loop -noxdamage -repeat -rfbauth PASSWORD_FILE -rfbport 5900 -shared -display :0
and using the default VNC server for Raspberry Pi OS, not changing any parameters.
I'm using the same RealVNC VNC Viewer as my client on my Mac for both systems.
The VNC client estimates: "Line-speed estimate: 26121 kbits/s (RTT ~0ms)" which sounds fast to me.
Ken: Thanks for the suggestion, but at this point I'd prefer not to run xpra, but rather keep the Ubuntu windowing environment.