The free version of CloudFlare does have some limitations. Most notably the free version cannot handle SSL certificates at your main domain. Linking CF into your site also adds another layer of complexity and
possible security hole - so not suited to everyone. Whilst only very minor, and quickly resolved, CF had a users account hacked in June 2012 so it is as infallible as any online system protected by a password.
There's also lots of optimisations you can make to a site to boost performance. Search for Google Page Speed for tips.
If your catchment area is global then choosing a fast UK web host with a Datacenter in London, UK will give you an excellent spring board.
We're hosting some
very popular sites out of our London DC right now for a UK Gov Organisation with global reach and looking at the various logs we're seeing very quick loading times from vistors corners of the Globe. (Its not the big Mother site but apparently we still cant say its name otherwise the events legal vultures will have us for scaps

Think sailing, Jurrasic Coast, Interlocked rings.)
Once you start getting traffic to your site, you'll be able to profile your users and adapt your hosting solution to suit.
Cheers
Rich