If it's intermittent, it's entirely possible that the slowdowns are a result of high load on our web cluster which happens from time to time. Next time you observe the slow page loads, make note of the time and we can check it against our monitors to see if a high load alert coincides with the time you noted.
One thing worth looking at would be to run your site through Google's PageSpeed insights
and see what suggestions they have. Setting up caching, minifying resources, and compressing images together can make a noticeable difference.
But if you want to PM me your current URL, I'd be happy to take a quick look at the site and see how it loads here from Sonic a few times during the day.