For Better Performance for Web Application

1) DNS Lookups - switch off
2) Don't load Modules, which are not needed.
3) Try to minimize the "Logging"
4) incorrect - DB Usage
5) unnecessary Remoting
6) incorrectly implemented "Concurrency"
7) Badly Performing Libraries
8) Excessive memory Usage..
9) Improper Caching
10) Unnecessarily usage of XML
11) incorrect APP Server - Configuration
12) Excessive Logging