Hi, I heard a lot of similar questions about drupal performance. Can agree that we are not able to create facebook using drupal, should mention that even pure php is not very suitable for this purpose. (As you know facebook created own php extension which compiles php code in c and execute it faster then native php interpreter.) Drupal is disigned for sites which have mostly anonymous users as main audience. There are sites like examiner.com which designed for logged in users. Such sites use drupal with mongo as db engine, but there are not too many of them.
If we need to disable drupal js or css compression for some roles we can use code below. Moreover we can change here ary settings from global $conf variable. For example you can change cache life time for certain roles or block caching. Any setting from this page http://yoursite.com/admin/config/development/performance can be changed in code given below.
Thank you for reading! Continue doing drupal!
Sometimes we need to flush cache on drupal site for one small thing become visible. And we had to clear all caches to make visible small change for block or for node field value. Now we have solution it is Cache Flush module. We can easily flush cache for block using "Flush cache" contextual link.