Thanks for both the comments ... Haven't yet had a chance to look at the first response properly though, but looks interesting, and will post back how that works out.

Meantime, yes, a particularly slow response can be got from the following domain: http://www.lxdirect.com

It used to be an active retail site, but they've now re-branded, etc. However, you'll wait up to 30 seconds or so for a response, at which point it fails (try it in a browser first if you like). It was only by chance that I realized that it was causing such a delay, but then figured I would need to handle such instances anyway ...