Site performance on Drupal, caching

Hello, Ivan. I'm reaching out to you again for help. I have a very heavy website on Drupal; are there any methods to improve the site's performance, perhaps using some modules? The pages load slowly. I've read about the Boost module. How can I set it up correctly and properly so as not to cause any harm? Are there any other methods? I reduce images, and I hardly use Flash. What is considered a normal page load time? Please advise. Thank you in advance!