You can check your website performances with SEOPress PRO right in your WordPress backend.
To do that, go to SEOPress, Pro page, Page Speed tab.
Click Analyse your site with Page Speed.
Wait few seconds, and you’ll get a full report about your site speed, advices, ressources stats…
You can send you this report by mail by clicking Send me this report by mail.
If you want to make another test, click Clear cache button (note that, Google also cached results for 1 min).