I`ve found that this service can cause links pages to load slowly (I'm using free service) adding about 10secs to the load time sometimes, this I felt was un-acceptable to visitors so have got around the problem by 'post' loading the thumbshots.
If anyone wishes to do this, just give the image an id and a local source, then use javascript and the 'document.images' function to re-assign the source. Obviously you need to use the onload function to call the function.