- History, tracking.
- Client side cache: Browser cache is not enabled for SharePoint library because it is SharePoint library is dynamic. You can use the http watch tool to analyze the http request.
- Server side performance: Due to client side cache does not exist, browse request the server for each user request instead of using browser’s cache, It will increase the network round trip, so it will impact on server performance as well. (We could overcome this issue with blob cache, you can find my other article blob cache on this).
- Versioning: needs to use free tools like SVN for change history and tracking.
I preferably like to have the files on _layout folder, Again it is depends on the project requirement, It is better to have the frequently changing files on SharePoint library for maintenance prospective.
Check this article on Dynamic HTTP Compression to enhance the performance of SharePoint portal.
You can find some good article for fine tuning the performance and cache sharepoint best practices
- Creating the custom theme in MOSS Branding
- Enabling IIS6 HTTP compression on SharePoint dynamic page
- Learn Sharepoint 14Hive folder structures
- Microsoft Sharepoint persisting webpart property values
- Adding Ribbon button in Sharepoint 2010
- SharePoint 2010 MSDN article collection for developer
- More about SharePoint Custom page and Application Page
- How to customize sharepoint list toolbar
- MOSS 2007 Best Practices
- SharePoint 2010 Virtual PC Setup