[insanebits]

I don't understand why custom solution seems to favourited by them. It's the same as saying your car is bad because it's running on the most popular fuel.

As a web developer working daily on WordPress websites I would argue that it can be as fast as anything else. Because those websites are mostly static which means caching would make it load really fast. Assuming template itself is written well. So it doesn't matter what engine you're using, it's the matter of optimization.

As for WordPress itself, the biggest problem in my oppinion is plugin compatibility. Yes you have thousands of plugins bus most of them doesn't work exactly/cannot be customized to a given requirements and you end up either modifying plugin and then maintaining them. Or just writing simplified version of it yourself. Which makes even more meaintenance overhead.

Also it's not very good for big blogs with more than 100k posts. Because of the database schema used which is both it's strength and weakness at the same time.