Try setting the following options within your DNN site's Host Settings area to improve site performance.
Expand the Advanced section and then expand the "Performance" settings section and set the following.
Page State Persistance: Page
Module Caching: Disk
Performance Setting: Heavy Caching
Authenticated Cacheability: ServerAndNoCache
Compression Setting: No Compression
Use Whitespace Filter: Unchecked or Disabled
Then expand the "Other Settings" tab and check the following.
Site Log Storage: File System
Site Log Buffer: 10
Site Log History: 14 days
Click "Update" at the bottom of your Host Settings page and make sure that your changes were saved.
