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Does Really Simple SSL make my site slower?

When you’ve activated Really Simple SSL on your site, in some cases you might notice your site has become slower. I specifically built this plugin to be fast: most of the work is done in the back-end, which doesn’t harm your performance. So why is your site slower now?

What most people forget is that when you activate Really Simple SSL, not only are you activating a plugin, but you are now also running your site over SSL! A connection over https is always slower, because of the encryption. A few things to note when checking your speed on SSL:

  • You should enable a .htaccess redirect for best speed results
  • Speed should be measured without the redirect, over https directly
  • SSL always causes a site to load a bit slower, as the server needs to encrypt the data
  • The way in which this impacts your site depends on your server, and on the efficiency of the site code

Important: check your site speed without the redirect!

In case you checked the speed for the http url: this will include the redirect in the speed measurement, which always slows down the site, and is not representative for the site speed: most users will start coming in over https. To optimize the redirection speed, enable the .htaccess redirect.

On tools.pingdom.com you can check what parts of your site are causing the delay. Often you will see a third party script loading very slow over https.

Actual speed impact of the Really Simple SSL plugin

On the front-end, most of the plugin code is not even loaded. Only two things are running: the redirect, which won’t kick in when the site is loaded over https, and the mixed content fixer. I have tested the mixed content fixer speed impact by saving the time on the “template redirect” hook in a variable, then subtracting that time from the “shutdown” hook, and logging that time 8 times.

  • Theme: 2017 default WordPress theme
  • Plugins: about 15 plugins random plugins copied from a customer’s site to give the site some “weight”.
  • Hosting environment: average budget hosting environment
  • 8 measurements

I have first just logged the time while commenting out all mixed content fixer code.

No output buffer, just time between the “template redirect” hook, and the “shutdown” hook. This is as if the plugin is not activated.

Average time delay between the two hooks: 0,187918752

Time between these hooks, with buffering, but no mixed content fixer. This is as if the plugin is fully active, but is just skipping the mixed content fixing code. 

Average time delay between the two hooks: 0,183732033

Time between these hooks, with output buffering and with mixed content fixer active

Average time delay between the two hooks: 0,180673395

I’ve dropped the lowest value in the last test, otherwise it would have come out lower  than without the mixed content fixer. Which would seem a bit odd.


Though the mixed content fixer of course has some impact, it does not seem to be enough to cause a major speed decrease. Of course, results can be different on other, heavyweight, themes/hosting environments. If you have more test results, measured in the same way, please leave them in the comments. Contact me if you would like the code that I used.

Actions to consider for speed improvement:

  • Enable the .htaccess redirect to optimize redirection speed
  • Limit the number of external resources (Facebook, Google fonts, hot linked images etc).
  • Check your console for external resources that are not or slowly loading over SSL
  • Consider using a caching plugin like Fastest Cache or WP Rocket
  • Consider moving to a faster server/better hosting plan.

Look at this site: pretty fast!

And take a look at the speed of really-simple-ssl.com. Does it feel slow to you? A test on pingdom tools show it loads in 657 ms, faster then 95% of the sites.

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  • Tommaso

    WP Super Cache plugin seems to fix the speed difference between “Fix mixed content” checked and unchecked. Indeed when I uncheck “Fix mixed content” function the site still service to my browser the old https link of the images, so I have to delete cached pages in order to get the new http link.
    Nice Job! Very happy to use this plugin

    • Rogier Lankhorst

      Thanks for the feedback!

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