Hey, abc1993, I’m another CF7 user.
I would recommend making a staging version of your site that you can play around with, in case you were worried about negatively affecting your live site, and also use for the comparison.
A staging site is a version of your site where you could play around with disabling plugins (disabling plugins one by one until you encounter an error or the problem is resolved, etc)/switching themes, etc and would be identical to your live site. You can make a staging version of your site with Local by Flywheel; get an archive of your site that you would use with Local.
Some hosts allow you to make a staging version of your site on their platforms.
If your speed is better on the staging site, keeping in mind to have identical settings on your live site when doing a 1:1 speed comparison, then your hosting service is at issue.
To also address the long server response time issue, you can try using a CDN, using a caching plugin or server caching and/or update your WordPress/PHP versions.
