With websites, the only speed-related thing that really matters is how long it takes to load a (front end) page. If that loading time is longer than a couple of seconds, most visitors will give up and not even view the page, so it might as well not exist. If they’re on a moving mobile phone or the page is really important or they’re an administrator they might cut you some slack, but as a rule of thumb two seconds is about the limit.
So, you need to measure that time with a tool like loadimpact.com or the Chrome “performance analyser” extension. If you’re trying to evaluate a host before you even sign up, then try to test some sites they already host, or sign up for just a month (beware of hosts that don’t offer any sort of trial period!).
Whether the storage is SSD or not is only a minor part of that equation.