site slowed down with boost

Hey @damax83

Could you share the error/behavior you are obtaining when activating Jetpack Boost, please?

I checked your website from our end and everything is connected and working.

Let me know if you have any questions.

My best regards,

Michelle

Hi Michelle thanks for getting in touch. So when its a clean slate my overall site score is in the medium-poor range. When I select the Optimise CSS option, I get a modest performance boost. Checking on Lighthouse confirms this, with performance improvements on both FCP & LCP.

When I turn on defer Javascript, the site performance score drops quite radically down, making the little pop out show which suggests I contact support. Checking on LH shows increases to FCP & LCP times. The weird thing is that LH shows drops in the amount of script processing time, but an overall worse performance score.

Lazy Load, I tend not to use, but as a tester, in conjunction with defer Javacript, it gave me the worst score of all with both mobile & desktop in the red, and a mobile score in single figures.

Today’s round of testing, just before I replied to you here, went slightly better, but still when I defer Java, I get an overall performance drop of around 13% compared to when only CSS optimise is selected, as you can see in the images.

CSS Optimise Only Turned On

CSS & Defer Java ON

CSS & Defer Java On (after a three minute wait & refresh)

Thanks for your assistance!

David.

Hi @damax83

Looks like there is something installed on the site that’s causing problems.

The best way to find out if something is interfering is to test for a theme or plugin conflict. You can do that by following these steps:

**Temporarily deactivate all plugins except Jetpack, and [clear your browser’s cache](https://wordpress.com/support/browser-issues/#browser-cache).**

– Then, try to activate Jetpack Boost again. If the plugin works, then you know another plugin is conflicting here. You can reactivate plugins one by one, checking to activate Jetpack Boost after each one to discover which plugin is causing the problem.

You can leave that plugin deactivated and/or contact whoever makes that plugin for help resolving the issue it’s causing.

If deactivating plugins doesn’t help, it may be your theme.

**Temporarily activate a default WordPress theme like [Twenty Twenty-One](https://www.ads-software.com/themes/twentytwentyone/).**

– Then, try to activate Jetpack Boost again. If the plugin works, then you know it’s a problem with the theme.

You can contact whoever makes the theme for help resolving the issue it’s causing.`