Drupal Optimization

I am glad to be part of a team who deployed Drupal as an Intranet platform for a Fortune 20 telecom company.  This is the first time that Drupal was used on an open surce LAMP stack to create a corporate Intranet for over 90,000 employees. The project was a complete rewrite of the existing intranet that had been in operation for over half a decade. It was accomplished in less than 12 months from conception to full deployment, ramping up from just a one member team to a 17 person group with only 5 full time developers

We all know that Poll is a core module which ships with Drupal. After installing this module we can setup poll and we can place a "most recent poll" block any where in region, usually its on a front page. I investigated this module and I found that it takes 20-25 queries to load most recent poll block and when a user submits a vote on that poll it does a cache_clear_all. Which was like WOW, in addition to submitting a vote users were also clearing my cached data. Optimizing or Caching poll's block for any kind of user (authenticated or anonymous) is like piece of cake, but figuring out how to do it was really a big pain in a neck.