WordPress vs plain HTML: dramaticall change in bounce rate

Hi.

I used custom CMS that generates static HTML files for the website.

Then I switched the website to WordPress, and the 'bounce rate' almost doubled and 'time on page' halved.

I compared pages generated by WP and the static pages using gtmetrix and google page speed. Both variants have almost 100 pagespeed scores and very close numbers in gtmetrix.

The google analytics code is located within the head section on both variants.

Page sizes are 277kb for WordPress and 213kb for static HTML (will all CSS styles and fonts)

What can cause such a significant change in bounce rate and time?

Thanks

 

When you switched to WordPress has the order of load for the page content remained the same?
This can be a factor which can drive off traffic if the elements of the page such as pictures or sliders load after the CSS or vice versa.
Check these factors and optimize them if they are not already optimized.

 

Switching to WordPress likely introduced changes in user experience, such as layout, navigation, or content structure, which might not be as engaging. Also, WordPress adds dynamic scripts/plugins that could slightly affect perceived speed or analytics tracking. Check mobile performance, plugin bloat, and traffic source changes.