I just ran your site through a Reverse IP checker and found that you have over 100 websites on the same server you have your site on. Although, this is no where as high as the record that was previously set by a user who had over 1000 websites on the same server as his site.
This means you're using a shared hosting plan/package from your host provider. The shared hosting plan/packages are not meant to be great on performance, but cheap hosting.
With web hosting you most certainly get what you pay and if you're unhappy with the performance, then I recommend you either upgrade your plan/package with your current host or change host. We recommend the following:
Also, regarding your issue with the popup media editor, I am unable to reproduce your issue, I have no problem clicking on it and it loading, regardless of how many times I click on it.