Then you'll need to check if your partition needs a defragmentation in really
# xfs_db -r /dev/sda5
xfs_db> frag
actual 22222222, ideal 2342342, fragmentation factor 99.9%
xfs_db> quit
Once you see a scary fragmentation factor, run the command for the optimization
# xfs_fsr -v /dev/sda5.......
This whill take some time.