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.

Try adding 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.

Code to fix slow dashboard in WordPress 3.5
wp-config.php code

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.

17 Responses

    1. I hope it works for you. It really solved my problems. WP3.5 introduced some wonkiness for me but I think it’s all running smoothly now.

  1. It’s pretty much worthless to update WordPress unless its not working properly.. WordPress updates are not focused on making wp lighter and faster contrary every update only bloats up even more then it already is.

    1. I’m glad that this was useful Pam. I’m still smoothing out some corners with 3.5.x, but things have been a bit smoother lately.

  2. I can let you know that this also works to speed up multisite networks. Great job… Was getting quite annoyed with the slowness of the dashboards.


      1. Hello again, I am sorry to say that it has gone back to being very slow, in fact it appears to be even slower than before.

        I clear my cache daily at work, and that makes no difference.

        The only other thing I have read online is that if you are using BT Business Hub for your internet connection that may also cause slowness.

        This does appear to be the case for me at work, whereas at home it is not as slow, but still noticeably slower than a normal install…

        1. Richard, have you already tried disabling your plugins (rename the ‘plugins’ folder in ‘wp-content’ to disable it all in one shot if you have quite a few plugins)?

          That might help quickly identify the root cause as a plugin problem (just dont’ forget to rename the folder back to ‘plugins’).

          You can also deactivate them one at a time from the Plugins > Installed plugins menu.

          I’d deactivate everything and see if the dashboard speed increases. If it does, then reactivate plugins one at a time until you find the culprit.

          Oh, might verify first that your ‘wp-config.php’ file still has the changes you made (make sure it didn’t revert to an older version without your code fix).

  3. Sorry I am not very experienced with editing code. I have a question:

    My config file ends with

    /** Absolute path to the WordPress directory. */
    if ( !defined('ABSPATH') )
    define('ABSPATH', dirname(__FILE__) . '/');

    /** Sets up WordPress vars and included files. */
    require_once(ABSPATH . 'wp-settings.php');

    So I placed the code for CONCATENATE SCRIPTS right before
    ‘/** Sets up WordPress vars and included files. */’.

    Is that correct? I followed the instructions to delete the cache and my backend is still slow, albeit under 3.5.1 now.

    Thanks in advance for any help you can give me!

    1. It looks like you have it right. I’m sorry it didn’t speed up things for you … it solved the problem for me. That being said, I’d begin disabling plugins – see if one is causing a problem. I do a quick and dirty check by renaming the ‘plugins’ folder located in the ‘wp-content’ folder to something like ‘plugins-old’. All plugins will be disabled in one shot. If the speed issue goes away, then you know it’s a plugin problem. Rename the ‘plugins-old’ file back to ‘plugins’ and try deactivating plugins one at a time until the culprit is found. You might look at some of these further suggestions : http://hecode.com/simple-ways-to-make-your-wordpress-faster/

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