As promised, here are the results of the possible performance enhancements that WordPress 2.1 has to offer. My disclaimers include the fact that these methods are mostly not very scientific and the server that this blog runs on also received a MySql upgrade before WordPress was upgraded. However, the results are stark enough that they still make a lot of sense.
The above graph shows the processor statistics of this server over a period of a little over four weeks. These are 2 averages of RRD data, collected every five minutes by a custom written script. The little spikes at regular intervals is caused by a backup process that runs every night and is not unusual. The first large spike after the beginning of the fourth week (which is relevant) was caused by a large amount of data being backed up due to the upgrade.
The actual upgrade was performed around the beginning of the fourth week, right where the processor usage went to null. There was some testing done before and after the upgrade along with some fixes to the various plugins that needed optimization and tweaks, especially Ultimate Tag Warrior (which had cause some performance problems and had bugs. Fixed thanks to Donncha’s help).
Now here is my really surprising conclusion. Average Processor usage for both user and system is less than half that of previous screencaps and records that I could find. In other words, not only is the system and the blog running much more steadily as indicated by the graph, the server is much less taxed and handles the load with half as much effort on average (even if we consider the rest to be margin of error). In real numbers, my previous average for user mode processor time was 26% and now it is about 10% on the daily average graph. This difference is more diluted to 20% previously and 13% at present for the 2 hour average graphs.
That is pretty cool!
[EDIT] Here are some more details on this server and traffic stats. This server is a dedicated P4 hyperthreadedÂ single processor server with 1024MB of RAM. The server is shared with a few other lower volume blogs and static pages but all of them were upgraded at the same time. No form of WordPress caching (beside query caching) is used on any of the blogs. During the aforementioned period, this blog received an average of 10,000 pageviews a day and all the other blogs combined saw an average of 5,000 pageviews per day. If there is any interest, I can provide what settings work best with MySql on my server.