@Joanna:
These might help and won't hurt:
* 'Vacuum' your Calibre Library metadata.db file by using the Calibre Menu Option: Library Maintenance > Check Library.
* Compress/Defragment your Calibre Library files using a Windows File Defragmenter, such as
http://www.piriform.com/defraggler/download .
* Compress/Defragment the external HDD on which your Calibre Portable 2.44 resides.
DaltonST