For all those (myself included) who thought that PostgreSQL wasn't as fast as MySQL for most stuff, Jonathan Ellis points to some recent benchmarks that show PostgreSQL to pretty much stomp MySQL all around, especially on SMP/multi-core processors.

If you don't bother reading the articles, simply note this single item:

We see, for instance, that adding a second Woodcrest in MySQL 5.0.20a - costing a good 851 dollars - only yields a 6% performance increase.

One of the comments in Jonathan's blog points to this thread: Single PostgreSQL server faster than MySQL cluster.

Personally I switched from MySQL some years ago for the features, finding performance to be adequate if not stellar. After recent experiences with both however I'd say that PostgreSQL now wins on all the following:

1. ease of installation, configuration, tuning and maintenance
2. features and extensibility
3. performance
4. stability

If you're a programmer, you'll find PostgreSQL to be the most amazing database around, bar none. The ability to program server-side procedures in a plethora of languages (including Python, Ruby, Perl, Tcl and more), terrific client libaries and API's for dozens of languages, and the MVCC approach (vs locking) makes development against PostgreSQL an absolute pleasure.

I chose PostgreSQL for these features in spite of performance doubts. Now that PostgreSQL clearly wins in the performance category as well, choosing it over MySQL is a no-brainer.