Really, this is just a link to the MSDN article “How to Optimize a SharePoint 2007 Web Content Management Site for Performance“. Nice easy title.
It does mention a particular irritation of mine – that many (most?) systems don’t use any kind of compression on static content. I remember seeing Apache admins complaining about people not using compression, oh, 10 years ago. In SharePoint, this is such a waste! JavaScript and CSS files are lovely and compressible – and core.js is big. So is Core.css. Doesn’t seem much reason not to enable it!
To do so, open IIS Manager, and right click on the ‘Web Sites’ folder. Select the service tab, and check the check box. Don’t go for dynamic compression; this would be a bad idea.
You’ll also want to check/edit the file types compressed. See Using HTTP Compression for details, and you’ll probably need to add the .JS and .CSS extensions.
I must sit down and give this a proper test some time. Certainly I don’t see the same sizes in the article, but then I’m looking at the file sizes on disc; in 12 Hive, and in the temporary compression cache (typically %WinDir%/IIS Temprorary Compressed Files). My numbers show Core.js to be 575Kb uncompressed, 91Kb after compression. Nice!
Andy Burns' Blog 
Third party tools like Ncachepoint can also be used for content optimization. The software minifies and merges multiples CSS and Javascript files for improved/faster page rendering.
The software externalizes BLOBs and boosts sharepoint performance using distributed caching. moreover, it caches Views, Lists and Sessions for even better sharepoint performance. By caching most data, sessions, etc , you really make Sharepoint give you much better performance than before, especially at peak load times. And you will not to worry about scalability because distributed caching increases both performance and scalability.