Web CMS Performance: pages/second (Joomla, Drupal, Plone, WP)

Question

Note: I am not into web programming, so forgive my ignorance in case the question is trivial. Also, please don't comment about "how flawed" the out-of-box comparison of these products is. The question is not about how they compete against each other, rather about the reason behind the incredible slowness of ALL of them.

Just read about a benchmark, where Joomla, Drupal, Wordpress, Plone3 & 4 had been tested. What shocked me is this: out of the box they performed around 4-14 pages/sec. How is this possible, why are they so damn slow? A CMS should just query a DB and churn out the data packed into nice templates. DBs are fast. Templates should be fast (text replacement, no big deal). Our machines are superfast and yet, these high profile CMSs could only produce a few pages/sec. How come?

Answer 1

A CMS should just query a DB and churn out the data packed into nice templates.

Not so much. Major, modern CMS systems are incredibly complex beasts. A typical page isn't merely body text and a title, but also dynamic category-based content queries that aggregate info across many site areas; not to mention security trimming and user-specific content zones. For example, loading http://www.volvogroup.com involves at least 7 of these queries, plus recursion through the site structure to generate navigation, and connecting to external systems to pull in news and investor relations data. Considering that, it shouldn't be such a surprise that it takes a beefy server farm to serve up several hundred hits per second.

Answer 2

Because it takes a alot of processing to do all of that. ITs not a matter of "query, replace, render". All of thes products are made to fit a wide range of use cases and to be extensible to some degree so really those 3 basic operations your are talking about are split up into many, many operations all of which consume time.

All things being equal - the more flexible he system the slower it will be "out of the box".