Thanks a lot, theducks.
After adjusting some preference in Calibre, it do runs faster but still far from satisfactory.
Then I discovered the "automatic management" feature of Calibre, which is great for me! I copy my books to the SD card directly and put it back to my T1 connected with Calibre, it then completed sending the metadata in a few seconds!
It brings me great relief as I don't need to wait for 30 hours or adding books to collections one by one.
