SharePoint guideline for optimum performance

Object	Scope	Guideline for optimum performance	Comment
Site collections	Database	50,000	Total throughput degrades as the number of site collections increases.
Web sites	Web site	2,000	The interface for enumerating subsites of a given Web site does not perform well much beyond 2,000 subsites.
Web sites	Site collection	250,000	You can create a very large total number of Web sites by nesting the subsites. For example, 100 sites each with 1000 subsites is 100,100 Web sites.
Documents	Folder	2,000	The interfaces for enumerating documents in a folder do not perform well beyond a thousand entries.
Documents	Library	2 million	You can create very large document libraries by nesting folders.
Security principals	Web site	2,000	The size of the access control list is limited to a few thousand security principals, in other words users and groups in the Web site.
Users	Web site	2 million	You can add millions of people to your Web site by using Microsoft Windows security groups to manage security instead of using individual users.
Items	List	2,000	The interface for enumerating list items does not perform well beyond a few thousand items.
Web Parts	Page	100	Pages with more than 100 Web Parts are slow to render.
Web Part personalization	Page	10,000	Pages with more than a few thousand user personalizations are slow to render.
Lists	Web site	2,000	The interface for enumerating lists and libraries in a Web site does not perform well beyond a few thousand entries.
Document size	File	50 MB	The file save performance degrades as the file size grows. The default maximum is 50 MB. This maximum is enforced by the system, but you can change it to any value up to 2 GB (2047 MB) if you have applied Windows SharePoint Services Service Pack 1. For more information, see "Configuring large file support" in Installing and Using Service Packs for Windows SharePoint Services 2.0.