We spotted that if you access our site under http:// it doesn't perform at all well, however if you access it under https:// it's absolutely great!
Perhaps this might help our server support people pin-point the issue. It doesn't, on the above evidence, strike me that this could be anything to do with needing to make server tweaks. We'd like it to perform like it does under https:// though but that isn't really practical, is it?
Regarding the SSL, we tried a few hosts but on their shared hosting they simply don't offer an SSL at the same domain as the site, rather you have to jump out to their shared SSL space at some awful URL such as https://secure.vaults1.com which I don't, particularly, like but maybe I'm being picky. I think it looks better if you've got the SSL certificate on the same domain as the site though.
Oh, I did try 1and1 Internet and, after two phone calls on hold for over 45 minutes, being incorrectly invoiced and then double billed by their accounts team, we decided to cut our losses! It really was a bad experience and I honestly couldn't recommend them to anyone.