> Question:  Does anyone have any idea what bottleneck I am hitting?  An
> index's performance should in theory scale as the log of the number of
> rows - what am I missing here?
    These can help people on the list to help you :
    - Your hardware config (CPU, RAM, disk) ?
    - EXPLAIN ANALYZE from slow queries ?
    - VACUUM and ANALYZE : yes ? how often ?
    - VACUUM VERBOSE output
    for huge bits of text with long line length, mail sucks, upload to a web
host or something.