[significant edits] Originally posted as a question, have founds some good documentation for help.
The new 15v4 is a 4K screen with very high DPI (PPI); bright; and very non-reflective screen!! Awesome! Just one problem: 4K HiDPI requires some extra work to look nice in Qubes dom0 and the VMs. And even after configuration, it’s still a bit rough around the edges due to some remaining tiny icons, cut off fonts, and other oddities. THIS DOCUMENTATION on Github is a good summary of what to do.
Here are the dom0 values and settings I thought were in the neighborhood of useful:
DPI at 288. A nice 3x integer of 96, which is recommended to avoid scaling problems with some programs
I even tried installing KDE to dom0, which seemed to cause issues, and looked like on its way to a system crash. Perhaps it was user error, I was changing a lot of settings. Finally, it looks like help is on the way, with XFCE 14.4 likely to be production released in a few weeks; hopefully quickly to be integrated into dom0. Supposedly it has been years since a major release, and they claim to have fixed the 4k and HiDPI integration problems.
Good to know.
I intend to install Qubes on my Libremv4 at some point, but I think I’ll wait until these issues are sorted out. My eyesight isn’t that great so “small unreadable fonts and icons” sounds like a nightmare to me.
I dabbled with Qubes for a month or so on a 15v4 and had the same issue. My solution, which worked reasonably well, was to:
change dom0 to KDE and scale the interface
using GNOME in my template VM’s, I scaled the resolution in gnome-control-center and/or increased font sizes with gnome-tweaks (i cant remember if it was one, the other, or both)
a note about the second one: i had to install gnome-tweaks into the templates, and then set the scaling within the AppVMs to get the settings to stick.
I will say that it was very usable with this configuration. I only moved away from it mainly for performance / speed reasons.
Part of your performance problems could be related to KDE in dom0. Qubes docs indicates that could happen. Of course, everything is more difficult and slower in Qubes.
LOL it sure is. I do love the security it brings, and KDE enabled some configuration that lessened the need to think about what VM you used for what, which was nice. In the end, I found that using a hardened version of another distro satisfies my concerns enough.