Sometimes, we see some servers that have good speeds of file delivery, but have very slow PHP processing, which basically makes the Imagevue scripts run slowly. In your case, and in my honest opinion, it is simply the delivery of files from your server that is slow (bandwidth related). I did some in-depth research on your website, and took a screenshot of loading times sorted from what takes the longest time to load:
As you can see in the above, what takes the most time is various static files (png, js and jpg). If you do the math for the speed of loading for those elements, you will see it is a poor result. Further down, you will see the PHP script files at ~4 seconds, which is probably below average also, but nothing noticeable compared to the general loading time of any files on your server.
In addition to the powerpack module (that loads a lot of files), you are using slightly heavy logo graphics and a lot of files are being loaded on start up. This would not necessarily be noticeable from a fast server, but in your case, with all these files loading and being served in queue by a relatively slow server, it sums up and makes it a slow load. If I was you, I would show this data to your host and ask them what's up with that ... Also, try checking your loading speeds at
http://tools.pingdom.com, as that will give loading indication from multiple locations.
All I can conclude is that this is not anything specific from Imagevue slowing down the loading ... Its just all those files being loaded and seemingly taking their time from your server.