I have experienced some great improvements to my Qubes OS running on a laptop with 16 GB of RAM and I want to share what worked for me, so that others might benefit from it.
When you start up Qubes the first time then all the system qubes and the internal management qube uses either debian-xfce or fedora-xfce. While xfce is a lightweight desktop environment, the system qubes can be optimized further.
Since I installed the debian-13-minimal template and used this template along with other forks I have experienced great improvements in boot up time, responsiveness and my OS no longer freezes once in a while.
The internal qube, default-mgmt-dvm, can use the debian-13-minimal template directly.
The remaining system qubes: sys-usb, sys-net and sys-firewall can use small templates based
on debian-13-minimal with some minor additional packages installed.
I recommend searching the documentation on minimal template qubes:
This doc has all the information you need, as to which packages each template qube should have.
My recommendation is to have one clone of debian-13-minimal template with installed
networking packages for sys-net specifically and then another clone of the debian-13-minimal
template for default-dvm that is used by sys-usb and sys-firewall.
While you are at it, install another minimal template from fedora-43-minimal, install all the
networking packages to it and use this template for another qube, sys-vpn, that you can
create and use for your vpn-connection - of course you have a such 
Also, I raised the maximum amount of available RAM to dom0 from 4096 to 8192 GB of RAM.
This also seemed to improve performance for me. I adjusted the maximum memory to dom0 with this command:
sudo nano /etc/default/grub
and then afterwards:
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
to update the bootloader.
But tread carefully making changes in this configuration file.
This works for me, but 4096 MB of RAM is probably fine for most people.
If you are reading this, you should probably just start out with implementing the minimal templates in your system qubes. This is probably the biggest increase in performance.
Hope some of this helps! 