on your very same hosting, i mean, your current hosting, upload in a subdirectory a brand new wordpress site, and do the same tests on that wordpress.

then compare with your other websites, and you can see if the problem is the lack of optimization of the websites.

About SSL, these days, all hosting are offering them for free, because they are free… if your hosting doesn’t, and you want to stay with them, you can ask a free SSL with clouflare or others, or just move to other hosting.