Off-topic, but since CMS-related submissions come up rather scarcely nowadays: What are some promising, modern Web Content Management Systems for medium-sized sites that I should look at, especially if I like the clean, modular design of ProcessWire very much, but not its implementation (too slow even with caching enabled)? I don't care about the programming language (PHP is fine, so is anything else). What I do care…
My suggestion is drupal, CMS with drupal is a good choice. yes there are multiple CMS choices and I tried a few of them, nothing beats Drupal due to its modular design, wide community, open source, various plugins, security updates,etc.
There is only one thing I miss from Drupal, and that is the ability to create new "content types" on-the-fly. But here lies it weakness too. The resulting DB structure that allows this is relatively complicated which means that any custom development you do outside of the normal Drupal stuff is also more complicated than it has to be. This also has a direct performance impact.
With Django (and by extension, django CMS), the structure of the database is as clean or complicated as you require, and, there's nifty tools for migrating the schema and/or data as you evolve your project. Its beautiful, really.