Hello, I've been playing with linux on and off for a couple of years, so not a complete noob, but still a bit out of my depth. Hoping someone can look at what I'm trying to achieve and suggest anything I haven't considered.

So, I use a laptop with 2 external monitors. One connects through the sole HDMI output on the laptop, the other connects to a USB 3 port replicator with HDMI output. When its docked I don't use the laptop screen.

At the moment I use Windows. For a few years now I've been playing with Linux in dual boot/VMs and I enjoy it and I'd like to ditch MS for good.

I am not married to any disto, I've played with a few of them (Ubuntu, Mint, Elementary, Fedora, Manjaro). I'd happily use any of them.

Problem is I just can't get my dual monitors working right. I have to use the DisplayLink drivers which are a PITA but they work on the Ubuntu-based distros. But the screen that uses them (the one on the dock) is laggy as hell to the point of being unusable and any time I have an application on that screen my CPU usage goes nuts. So it 'works' but it's not usable in any real sense. This is a known issue with DisplayLink and Xorg and isn't likely to get resolved anytime soon/ever so far as I can see.

I've done a lot of googling, played around with settings, copied and run stuff in terminal that I didn't understand...I just can't seem to get past this roadblock.

It's driving me bananas that this, of all things, is the barrier to switching to Linux for good.

My laptop has no other video output, no USB-C. At the moment the only options I see open to me are

1. Buy a new laptop with USB-c so I can stop using DisplayLink
2. Buy an ultra-wide monitor and use that instead of the two I have.

I don't want/can't afford to do either of those things! If anyone has any better ideas I'd love to hear them and would be so grateful, cheers.

I don't use dual monitors myself, but my Raspberry Pi SBCs can do dual monitors, & they use Debian, so I suggest trying with that.

I also use RPi 4B SBCs and they do dual HDMI out of the box. (~$150 for a full setup canakit version).
The RPi 4B runs Debian (RaspiOS) by default, but is also capable of running Ubuntu 20.10, Fedora 33, and others, all in 64 bit. With Fedora it is even capable of booting from USB, although I have not tried the others.

The RPi4B & RPi400 can both boot from USB - (as can the RPi3 series, if you set the 'bit')

But here just talking about which distro, likely more do, but certainly Debian.

Thanks for the suggestion, the Raspberry Pi 4 had occured to me but I kind of wrote it off since it seems like asking an awful lot of it to be a daily workstation. But I may well have to give it a try...

Yeah, I have not tried the pi3 and since the pi400 is a 4B in a keyboard I naturally assumed it would be the same.

Just a thought on this: have you tried just connecting an HDMI display + the laptop's built-in monitor? Very likely that 'USB connection' is actually a USB videocard (which will of course be sold as 'USB to VGA adapter' or some nonsense - like all USB devices expect lowest-common-denominator approach to advertising its function), and the issue is likely driver-related. I'm wondering if setting dri_prime to use the laptop's GPU (vs whatever is in the USB 'box') may help (read around in here: https://wiki.archlinux.org/index.php...as_Primary_GPU and here: https://wiki.gentoo.org/wiki/AMDGPU#...card_is_in_use - expect to do some poking around in the terminal if you want to test this out), or if you've tried that, but otherwise this is probably an example of Windows-specific hardware - it's not linux's fault (it's actually not even really Windows' fault) that the designer was lazy and hacked on it just enough to get it marginally working in Windows and then quit...(and it will probably break in later versions of Windows at some point too as a result).

What other ports does your laptop have? Any chance you can use an external GPU? Or DisplayPort MST?

If you feel like jumping down a rabbit hole with old hardware, this may also be a starting off point:
https://askubuntu.com/questions/5548...rking-in-linux (I have never used one of these Matrox boxes myself, but I have one of their AGP cards that has similar functionality (that card only works in windows that I'm aware of), and while it really will give you multiple monitors from a single VGA or DVI port, it is far more limited than 'true' multiple outputs (it treats them like one big monitor and has significant limits on resolution and refresh rate).

Another off-the-wall idea is to consider Barrier (https://snapcraft.io/barrier) if you have another machine/monitor and your use-case makes sense (you won't be able to drag windows/applications between the machines, but you will have a single cursor and keyboard and can copy/paste back and forth - depending on what you're doing it's 'good enough' in many cases).