In the past couple of days, many client sites have gotten notices from Google Webmaster Tools about being unable to access CSS and JS files.

The most widespread issue was blocking of wp-content, wp-includes and wp-admin in the robots.txt file. Googlebot is now smart enough to not crawl these items by default, so they can be removed.

The second issue we found was related to the Wordfence plugin. As of version 6.0.12 Wordfence includes a call to a dynamic script located in wp-admin, which is a default “Disallow” entry in the WordPress robots.txt file. Upgrading to Wordfence 6.0.14 or later will fix this issue.

Users of WPCmdCtrl are already covered and have the update 🙂

Updated June 14. Added results for W3 Total Cache using Disk Enhanced caching only at the request of Frederick Townes, author of W3 Total Cache. I ran tests with both “gzip” and “gzip and deflate” settings.

I’ve seen a lot of discussion lately about the various WordPress caching plugins. Here’s a quick comparison using Apache Bench. First some background on the test platform.

This is a 512mb VPS from prgmr.com

Fresh install of Ubuntu 10.04

NginX, PHP, MySQL installed via APT (PHP 5.3.2-1ubuntu4.2ppa3~lucid1 (FPM/FastCGI), NginX 0.7.65, MySQL (5.1.41-3ubuntu12.3))

WordPress 2.9.2, standard Kubrick theme, nginx Compatibility plug-in installed.

Plugin Versions:

WP-Cache 2.12
WP Super Cache 0.9.9
W3 Total Cache 0.8.5.2

The following command line was used. The -c and -n flags were modified during different runs as illustrated below.

100 Concurrent Requests

250 Concurrent Requests

250 Concurrent Requests – 10000 Total Requests