Gnome animation effects are laggy under 3840x2160. I believe it would work well with 1080p, although I didnt try it(I have another machine with hd620 that works well with 1080p).
It is more about hd620 than 7500u. Cpu usage is not very high when the lag happens.
Besides, it seems that gnome Xorg session perform better than gnome wayland session.
Any ideas to tweak this ?
wayland under gnome should have better animations than X (i mean more fluid - i had no problem with it - 4k@60 on my AMD iGPU)
I’m not using a Librem but I am using Intel integrated graphics. I found the same using Wayland compared to Xorg, and performance is pretty terrible for me at 4K. So I am also interested to hear any suggestions.
Update: I finally switched to 1920x1080@120Hz.
It is so good, all except there are some blurred fonts (compared with 3840x2160).
I will stick to it.
Have you seen much of a difference in battery life? That’s probably the main reason I use 1920x1080.
I dont use battery that often, but I did notice the temprature and noise is down.
I tested it with glxgears and it turns out to be 60Hz. Xrandr gives out the same result. Not sure why gnome call it 120Hz.
Just don’t use Gnome. My only computer on which Gnome was don’t laggy - Intel Core i7 4820K, Nvidia GTX 1070, 2560x1440@144. Any other computers have microfreezes and some kind of lags with Gnome.
I decided to deny Gnome when i sell off my computer, ordered Librem 15v3 and i was forced to use little laptop with Intel Atom N570 and HD Graphics. Xfce4 works very fast, and eat very small amount of memory. But Gnome looks nicer than Xfce4. =(((
Also, check this link. This tool allow to set lower resolution withour blur.
I used to be a xfce4 user when I was using archlinux as my main distro. But, well, gnome looks so much nicer 
Besides, I cannot compile the repo in the link. My stock xrandr version is 1.5.0
You can get sources of your native “xrandr” and change some lines in code. You need to change “filter” varriable to “nearest”. In this reposiory, varriable was set to “nearest” in 1259 line.
it seems the the newest version of xrandr provides a --filter option, while my stock xrandr does not.
I would try to use xrandr from git with --filter nearest first, before applying the patch
XFCE doesn’t have to look bad!
https://www.reddit.com/r/unixporn/search/?q=xfce&restrict_sr=1
My lovely combination of themes for Xfce4 - “arc-theme” and “papirus-icon-theme”. All themes exist in Debian repository.
You might try to disable display compositing. I had problems with smooth scrolling on 15v4 Qubes until disabling compositing.
I don’t use compositor too, only TearFree parameter for Intel GPU. Also, i recommend to switch to “glamor” acceleration, because it better than “sna” ("sna is default) on big resolutions. I can easily use 2560x1440 external screen with 1920x1080 build-in screen in “extend” mode.
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "TearFree" "true"
Option "AccelMethod" "glamor"
EndSection