Why do we do final in Java?

Noticed lots of nice opensource code and Java style checker suggested to use final and static as much as possible.
I kinda understand why to use static, especially for methods, but not sure why final will help.
After a bit of google, I found the following claim at:

http://www.javaperformancetuning.com/tips/final.shtml#REF1

From: http://www.protomatter.com/nate/java-optimization/
Various tips. (Page last updated 1999?, Added 2000-10-23, Author Nate Sammons, Publisher Sammons). Tips:

Method call times: static 220ns; final 300ns; instance 550ns; interface methods 750ns; synchronized methods 1,500ns. [But times vary enormously depending on the VM and context].
Use static final methods where possible. [And do functional programming too ;-)]

Since the note was added around 1999 and 2000, I'm wondering it still stand true or not.

Now matter what, I will try my best to apply this policy to my code. But if anyone can explain why to me, it will make me feel much better.

Thanks!