Unfortunately, I am not seeing any issues. Navigating around your community seems fine. The page loads extremely quickly, the only delay is once the software loads and your advertisements and third party JavaScript loads in.
However, the fact that it is erratic seems to point more towards a server problem than to a code problem. If it was due to a poor performing piece of code, that would be slow each and every time you use that specific page, function, etc... I would continue down the route of your hosting provider as they have the tools and responsibility to troubleshoot this. If this is outlined as an issue with our software, we will require the supporting log entries which they determined this from to advance our troubleshooting.