PS: Best configuration to increase drupal's site performance


I have just signed up to Dreamhost Private Servers (PS) because my site, which is running drupal, was needing more memory to prevent 500 errors.

I’ve seen that PS offer some features that sound interesting in their description, such as lighthttp or Xcache and I would like to know if there is any drupal user who also reads this forum that can tell me which is the best configuration to increase drupal’s performance and if there are any drawbacks on this.

Thank you very much