After using using Liferea for a while, it tends to slow down during startup. This is most probably caused by the sqlite database it uses becoming fragmented. Using the sqlite VACUUM command helps solve this.

To run this, do the following:

  1. Shutdown liferea.
  2. Run the following command: 
    sqlite3 ~/.liferea_1.4/liferea.db "VACUUM;"
  3. Load up liferea and feel the speed difference

Source:
Liferea Developer blog