I have Arch Linux installed on a USB 3.0 flash drive - not Live USB, but persistent installation. I have been using this install for a half a year without any issues on an Acer R 15 (i7 CPU, 12 GB RAM) laptop, it runs great. The USB drive is 8GB only, so I have run into disk space shortage and decided to move the install on a freshly bought HP USB 3.1 32GB drive (CrystalDiskMark and hdstat showing 190 MB R / 100 MB W). I have set up partitions and moved the existing system with rsync -aAXv /* /mnt/new_usb --exclude={/dev/*,/proc/*,/sys/*,/tmp/*,/var/tmp/*,/run/*,/mnt/*,/media/*,/lost+found}, reinstalled linux init images and grub.
The system boots ok from the new medium, but it is very slow - it used to boot within ~ 15 sec from the old 3.0 USB drive, and now it boots within ~ 2 minutes, with many processes stuck for several seconds at startup (I can see it with systemd while booting). Booted into XFCE, it resembles working at old machines - Chrome startup in 20 - 30 seconds, spontaneous lags while scrolling screens, starting up programs, updating software with pacman, scrolling bash history etc. Hdstat still shows high R/W numbers. I can clearly understand this may go if I installed the system from scratch, but I really need to have it cloned other than reinstalled.
How do I determine what causes this behaviour, and fix it?
