Sometimes, you face performance issues and feel lost, but you should never feel alone when working with one of the most successful open source projects ever.
If you need to get some advice on your performance problems, then the right place to do so is the performance mailing list at http://archives.postgresql.org/pgsql-performance/.
You may want to first ensure that it is not a well-known problem by searching the mailing list archives.
A very good description of what to include in your performance problem report is available at http://wiki.postgresql.org/wiki/Guide_to_reporting_problems.
More performance-related information can be found at http://wiki.postgresql.org/wiki/Performance_Optimization.
Another good reference for performance-related information is PostgreSQL 9.0 High Performance, Packt Publishing.