99% sure this is a Mint theme issue
Fedora has similar behavior. this is not related to the theme of the design Linux thinks that the program is frozen during rendering, it is treated by increasing the waiting time. but this is a crutch
I’ve installed KiCad v8.0.7 in Mint 21.3 and Mint 22
My 3D viewer of a big project (6-layer 300 x 550mm PCB) takes 13s (Desktop Mint 21.3) and 14s (Laptop Mint 22).
I think hardware plays an important role here
Mint 21.3 HW/SW info
Application: KiCad PCB Editor x86_64 on x86_64
Version: 8.0.7-8.0.7-0~ubuntu22.04.1, release build
Libraries:
wxWidgets 3.2.1
FreeType 2.11.1
HarfBuzz 2.7.4
FontConfig 2.13.1
libcurl/7.81.0 OpenSSL/3.0.2 zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0 (+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3 OpenLDAP/2.5.18
Platform: Linux Mint 21.3, 64 bit, Little endian, wxGTK, X11, cinnamon, x11
OpenGL: AMD, AMD Radeon RX 6600 (navi23, LLVM 15.0.7, DRM 3.42, 5.15.0-130-generic), 4.6 (Compatibility Profile) Mesa 23.2.1-1ubuntu3.1~22.04.3
Build Info:
Date: Dec 3 2024 15:56:08
wxWidgets: 3.2.1 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.74.0
OCC: 7.6.3
Curl: 7.81.0
ngspice: 43
Compiler: GCC 11.4.0 with C++ ABI 1016
Build settings:
Mint 22 HW/SW info
Application: KiCad PCB Editor x86_64 on x86_64
Version: 8.0.7-8.0.7-0~ubuntu24.04.1, release build
Libraries:
wxWidgets 3.2.4
FreeType 2.13.2
HarfBuzz 8.3.0
FontConfig 2.15.0
libcurl/8.5.0 OpenSSL/3.0.13 zlib/1.3 brotli/1.1.0 zstd/1.5.5 libidn2/2.3.7 libpsl/0.21.2 (+libidn2/2.3.7) libssh/0.10.6/openssl/zlib nghttp2/1.59.0 librtmp/2.3 OpenLDAP/2.6.7
Platform: Linux Mint 22, 64 bit, Little endian, wxGTK, X11, xfce, x11
OpenGL: AMD, AMD Radeon Graphics (radeonsi, gfx1103_r1, LLVM 17.0.6, DRM 3.57, 6.8.0-51-generic), 4.6 (Compatibility Profile) Mesa 24.0.9-0ubuntu0.3
Build Info:
Date: Dec 3 2024 15:56:02
wxWidgets: 3.2.4 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.83.0
OCC: 7.6.3
Curl: 8.5.0
ngspice: 43
Compiler: GCC 13.2.0 with C++ ABI 1018
Build settings:
For me it is okay, excellent performance in both cases. Especially considering that this is a somewhat extreme project.
I cannot see OpenGL references in your version info. What is your graphic card and CPU?
The systems are different, the hardware is different, but the behavior is the same on all of them. The board file is linked. Open the standalone board editor, convert it to a Kikad board, then run 3D viewing. I checked it on three different machines. linux mint 22 ,fedora 41 ,ubuntu 24.04.1
After importing PcbDoc and saving the kicad_pcb file my PC takes 300ms to get the 3D image.
What is the question or did you show me that it was displayed?)
At this point, the system thinks that the application has frozen and displays a sign
its showing it is working, which points to a local issue rather than a kicad general issue.
Either your drivers, themes etc isn’t really compatible.
Can you make a local temp user to see if that works? can you check your drivers (eg glxgears?)
rendering takes about 20 seconds when creating a folder from a detail (for the first time) this does not depend much on the power of the PC since it does not work in multi-thread
Okay but what about your graphic card & drivers?
20 seconds for the first time could be a long time for your project but after saving kicad_pcb file times should be much less.
as I wrote earlier I used different machines with different cards rx6400, nvidia, intel this does not affect the rendering time it is about 20 seconds on all three cards. at this point after a long wait a notification appears the system thinks that the application is frozen.
The force quit / wait modal dialog in linux appears when the system runs out of resources. It’s a kind of timeout that ables you to kill the process or just wait. Obviously this could happens on any app. IMO the case is closed: Kicad is free and not guilty 
this can be reproduced on win if you try to do something in kicad during rendering. This is at least not normal behavior and a known problem of kicad and not the operating system as a whole. an error or incomplete code if that is more convenient. (multithread is needed)