Do the long shutdown time occur after having used Windows?
Unless shutting Windows OS down cleanly, various operating system state values is written to NVRAM - one speculates if such value could be causing confusion for the Linux OS - especially for the onboard wifi.
linux kernel
I recall seeing topics on Ryzen 9 7900X and as your system is on Linux 6.12.4 - you are on stable branch.
I saw from a topic a link to phoronix that 6.13 would bring some long awaited features for these Ryzen cpus.
To improve your experience - I suggest you switch to testing which has Linux 6.13.0rc7-1 (unstable has 6.13.0-1)
sudo pacman-mirrors --api --set-branch testing
Then run a full system sync adding Linux 6.13
sudo pacman -Syu linux613
After this has succesfully finished
reboot
watchdog
You may improving performance by removing the watchdog.
You may edit /etc/default/grub and add nowatchdog
sudo nano /etc/default/grub
In addition to the existing arguments insert (the dots illustrate the existing content)
GRUB_CMDLINE_LINUX_DEFAULT="... nowatchdog ..."
In additions to nowatchdog one should add a file
sudo nano /etc/modprobe.d/blacklist-watchdog.conf
Add the blacklisting of watchdog module
blacklist iTCO_wdt
Save the changes and rebuild grub.cfg
sudo grub-mkconfig -o /boot/grub/grub.cfg
Then restart your system to test the changes.
mitigations=off
Another method to improve performance is to disable CPU vulnerability mitigations by adding mitigations=off to the kernel cmdline (remember to rebuild grub configuration)
sudo nano /etc/default/grub
In addition to the existing arguments insert (the dots illustrate the existing content)
GRUB_CMDLINE_LINUX_DEFAULT="... mitigations=off ..."
Restart the system and test the changes