Since a fresh install of 4.3, as a few have mentionned here, sys-usb is a lot slower than 4.2.4. I did follow the recommendation to stop and disable the minimal-usbvm but still, very slow transfer speeds. the througput was about 30mb/s for an external NVME. This estimated a copy of about 1 hour. Ran the same copy on a non qubes os computer with the same external NVME device and it copied in 15 minutes. The qubes backup also took a lot longer than I expected. This is not a super big file, we’re talking 134 Gigs. I know a lot of work has been done in sys-usb for 4.3 but the 4.2.4 version was really faster for me. Hopefully this will be adressed in a future update