Hi there,
GeneratePress is known for being the lightest theme available, so changing theme isn’t going to make any real difference. And you risk Google having to recrawl the site due to any HTML changes. Read on below and you will see the Theme is not what is causing you delays:
You should take the time to look into what exactly is causing a delay on your site loading times and improve those issues.
Running a pagespeed test on your site will help:
https://pagespeed.web.dev/report?url=https%3A%2F%2Fcpstester.fr%2F
the are two main opportunities are:
Reduce unused JavaScript – the majority of this is codes for adverts, google analytics and some custom codebase.js
Eliminate render-blocking resources – these are primarily stylesheets from plugins and there is a custom stylesheet for codebase, and it also looks to be loading bootstrap framework.
So you have custom code, plugin code, advert code, analytics and other 3rd party resources that take up most of your loading time. And all that code will still be there if you change to any theme. So swapping theme is not really going to help.
You should:
replace any plugins or custom codes – codebase.js / CSS files are big on your site, i am not sure what you can do there.
Use optimization plugins to:
Improve loading of renderblocking assets
Defer / Delay loading of 3rd party advert and analytics scripts.
Load google fonts locally as those too are reducing loading times, most optimization plugins handle this or you can follow the guide here
I hope that helps