Just a short note on what we are doing for 1.8. Right now we try to reduce startup time by killing costly cleanup stuff done on startup by cleaning up the DB schema and we are also thinking about a good way to periodically vacuum the database on startup. The problem there is to find a good interval and to avoid doing it too often as it costs time even if the DB is in a 100% clean state.
If you want to test try running SVN trunk which performs a cache migration to the new DB schema. By reducing the schema by one unnecessary table we now skip some consistency checks which sometimes took around 10s of startup time.
If you do test it please post us some comparison values in the comments! You can gather the startup time by launching both 1.6 and trunk using this command:
liferea --debug-db --debug-performance | grep "startup took"