I just upgraded from PostgreSQL 8.3 to 9.2.  In doing so, I also went from a Sun optimized build (since I installed their supplied version before) to a self built version where I didn’t fiddle with optimization at all (the documentation suggests -O5, but I let it go with the default of -O3).  Despite the lazy build, it seems a lot faster in terms of the queries some of my python code executes.