Well I'm not sure exactly what it is but a twitter search has confirmed it is not just me.
Cloudflare sites (including reddit) are being very very slow and most requests end with a gateway timeout.
Akamai CDN is the same (facebook images, twitter images)
See traffic map here: http://www.akamai.com/html/technology/dataviz1.html
21:42 BST - 4/6 European cloudflare datacentres are currently offline.
21:49 BST - It has been reported that Telias Transatlantic cable is down
21:51 BST - Cloudflare confirm that Telias cable has been cut
21:56 BST - Traffic now being rerouted