I constantly run speed tests on my websites and blogs. I tweak settings, monitor changes after updates, and look for ways to keep making improvements. There is always room for improvement, and I find that my biggest speed issues tend to surface after running updates.
If you're having speed issues with your WordPress blog, chances are good the problem stems from your theme or one of your plugins. If that's the case, there's a simple tool you can use to pinpoint the culprit, and it happens to be one of my favorite plugins:
This plugin evaluates the load time of all of your other plugins, your theme, and the WP core. That lets you see if any particular item is causing your slow loading times. Here's an example from this site:
As you can see, the plugin taking the most time to load here is currently WordPress SEO by Yoast. But remember that this information is relative to the other plugins you're currently using.
You can get more detailed info on each plugin (and your theme's load time) by exploring the other tabs in your report. For example, WP SEO is taking .8 seconds to load. While it's not as fast as I'd like it to be, it's not nearly slow enough for me to want to replace it. The pie chart simply shows that my other plugins load much faster than that.
Last year, I noticed a slowdown on several of my blogs, including those using caching plugins. I installed the P3 plugin and found out the problem was a recently-updated social media / sharing plugin. I was able to choose another option and replace it on all of my blogs. Their load speed improved right away.
What's slowing your blog down? Install the Plugin Performance Profiler to find out if your issue is as simple as replacing a plugin. This is far from the only thing you can do to increase your WordPress blog speed, but it's a simple step in the right direction.
After using the tool, did you come across any surprises? How slow would a plugin have to load for you to consider replacing it?