File indexing (e.g. via tracker3 on Debian) uses quite a few resources and is pretty useless in a dvm qube, such as sys-usb, as it will have to start over every time the qube is started and it may block certain operations, e.g. for me it often blocks veracrypt volume dismounts (volume is on external storage and mounted in sys-usb; when trying to dismount it, it fails saying that the volume is busy). Therefore it may be useful to just turn that off:

In your dvm-template (e.g. debian-12-dvm; I only tested for Debian 12, not others) start a terminal and run the following commands:

systemctl --user mask tracker-extract-3.service tracker-miner-fs-3.service tracker-miner-rss-3.service tracker-writeback-3.service tracker-xdg-portal-3.service tracker-miner-fs-control-3.service

and then

tracker3 reset -s -r

and then shut down the dvm-template. Be sure that you did this in the dvm-template, e.g. debian-12-dvm, and not in the base template, e.g. debian-12!

The next time a dvm-based qube, e.g. sys-usb starts, it won't have tracker3 running.

Important caveat: tracker3 does more than just file indexing, e.g. helps with search and rename, but so far for me normal search, including in nautilus still works, but just be aware that there may be side effects.