Different caching parameters:
- Enable the BlobCache in web.config to create a disk cache for all pictures, style sheets and scripts that are used => Reduced database traffic.
- Consider reducing the number of application pools used to relase more memory on the server(s). Each application pool is assigned a unique worker process which again loads the runtime => More memory for caching the "real stuff" :-)
- Set the correct Caching profile on each web site - from the Admin page => Quicker page loads.
Web parts and customizations
- Write your web parts and custom controls and pages such that the do as little data processing as possible before the user makes an action. => Reduces the time to load a the page that are using your web part/component.
- Depth of the web site hierarchy => Content by Query and other querys will run quicker