I would like to know your thoughts on Drupal and its performance, and especially how to improve it.
We currently use a system based on Drupal 6.22 Project Mercury (Pressflow, Varnish, APC ...) specially designed for heavy traffic. And we have installed more 50 modules like (Views, CCK, Panel, VBO, Rules, Workflow, UberCart, Solr…)
But our production server is a virtual environment with 4 CPUs and 8 GB of Ram, which is really huge for a single site. During our peak traffic, we have over 1,800 visits and more than 50 connected users for one day.
We are always looking for information to improve performance and to reduce costs.
If you run a high traffic website, I would like to know your point of view and your working methods or tips to improve performance.