How scalable is Plone?
Plone is appropriate for very small websites and very large ones. Plone has powerful built-in caching features that can be configured to optimize site performance. In addition, Plone site administrators often use web accelerators such as Squid and Varnish to boost site speed.
Thanks to its use of Zope, Plone has outstanding clustering capabilities, which allows a website to be split over multiple servers to handle high traffic.