Site and Wordpress slow to load

Hi,

I'm having trouble with my website. It is slow to load (and so is the wordpress desktop). I don't know if this is related to the theme, but I didn't have these problems with a previous theme. I've been in touch with hosting provider and they don't think it's a problem at their end. I am not running super cache. Any suggestions?

http://understandingcancer.co.uk

Thanks