We need a good CMS that supports data clustering (managing and storing data on different servers). By "good" , I mean : reliable , minimum bugs , the faster the better. (Oh , and it should make coffee :) )
I am not sure about "Performance-oriented" means for you. There are sites with Drupal and Joomla that receives million of visits month after month, and do not need special configurations like data clustering.
I think you must ask yourself if you need all you said.
For reliability, and no bugs or minimum bugs i can stand for Joomla.
I think the performance is a function of the hardware.
I agree, and I think that you need to look for software to fit your need. I have a few sites that only get minimal traffic that run on WordPress, but I also admin a site that runs Joomla and gets reliable amounts of traffic.
Also, Joomla has a wonderfully customizable interface with extensions, plugins, themes and a fairly easy to use administration tool.
Yes … kitchen sink + community + support: Plone. Development heading very much in the right direction.
Plone is in some ways a different creature from many other systems. Depending on the environment, ultra-high performance may require some attention but in the community there's great expertise to steer any attention that may be required.
http://plone.org/support | Chat Room is a great venue for diverse and honest advice on this subject. We regularly steer people away from Plone -- when some other system will better suit their needs.
When you get to data clustering levels, your better off doing some real testing of CMS systems.
Most of the bigger names support a lot of things. MS CMS Server, DotnetNuke
Anything used by really large shops should work.