Has anybody used Expression Engine on a large scale project?

Haven’t used it. I highly recommend ModX, if you’re still prospecting. www.modxcms.com

I used to use it to power my freelancing blog (which is no longer online). I liked it well enough, though I’m usually averse to having to learn someone else’s idea of a templating engine.

I know the Method Arts guys (of whom the designer of this site is one) use EE on a lot of projects and they love it. Here’s one EE driven site they built: http://miox.com

I think all of the EllisLab’s sites are powered by ExpressionEngine, and I think they’re also fairly popular, so they probe that it can be used on large/high-traffic sites… for instance, check CodeIgniter

On the other hand, there are many, many factors that could influence the performance of a web site, like hardware, web server (Apache, lighttpd), database, cache system (eaccelerator, memcache, etc.)... and even things like the template you’re using or whether your CMS has a built-in option or a plugin to generate static HTML files.

Some time ago I made a comparison between Drupal, Habari, NucleusCMS, Serendipity, Textpattern and WordPress to measure how many requests they completed on 30 seconds, and posted the results on Evaluando el rendimiento de algunos CMS, which is in spanish but includes a really clear graphic and a table with the results. I have to say that the difference between a regular WordPress installation and another using WP-Cache it’s really impressive, so if you would like to try WordPress on your project, make sure you use WP-Cache.

What felipelavinz said! Caching can make even dog-slow sites plenty fast. My company (we’re hiring, btw!) recently built a site using Symfony (which isn’t exactly known as a speed demon) and were able to scale it pretty darn well through smart use of caching (in our case, a combination of built-in Symfony caching and memcached).

Thanks! By the way, if Yahoo! chose Symfony for the new version of del.icio.us, I think we can easily assume that they made sure it can scale ;)

If you are smart enough and/or have enough money and/or enough knowledge, you can even scale Ruby on Rails apps, like twitter… well, kind of ;)

Yes, memcached is like magic zoom zoom juice for your website.

There are a lot of large sites that use ExpressionEngine successfully:

http://www.hopstudios.com/blog/item/the_10_largest_expressionengine_sites/

TTFN
Travis