Thanks Mr Tengler. That's exactly the kind of answer I was hoping for. That's a busy shop and a level we hope to reach in a few years time. I was starting to wonder if anyone was using Prestashop on large sites, or if it was being used by small businesses only and all its scalability was pure theory.
On a side note, since you're managing 14 domains, please can you guide me on how you've setup multiple domains. It's easy to add a second store as a folder (domain.com and domain.com/uk/) but adding a whole new domain seems to need some preparation. I've tried adding a domain in the settings, but it doesn't allow me to do it so I assume I'm not properly set up to allow for multidomains.
Do I just point the DNS records at my multistore's server, or do I add the domain as an Addon in cPanel, or do I need a separate installation of prestashop for that domain and just add it to my multistore? So many options... not a clue where to start.