WordPress 3.5 Slow Speed – Fix
Today, when I began working inside the dashboard of WordPress 3.5, I found a snail.
For some reason, everything inside the dashboard began operating at a snail pace. “Another plugin conflict?” I asked.
For this problem, I found a handy suggestion.
define('CONCATENATE_SCRIPTS', false );to the bottom of your wp-config.php file (just before the require_once line).
esmi, WordPress forum
I know others are experiencing this issue too. I can say that it appears to have fixed the problem in my case.
My wp-config.php snippet looks like this. The wp-config.php file is inside the root directory of your WordPress install. I used BBEdit to add in the code, but feel free to use your editor of choice.
After, making the changes, I also cleared the cache. In this case, I was using WP Super Cache. I went to the Settings > WP Super Cache > Easy tab and clicked the delete cache button.
The dashboard has returned to normal speed now for me.
Hopefully, this will help you out too if you’re experiencing the slow dashboard speed problem after upgrading to WordPress 3.5.