Optimising PHP Scripts

Mainly to avoid generalised coding for better usage of memory and time, use specific and proper logic, statement, inbuilt function.

1. Take advantage of native php function
2. Cut out unnecessary classes
3. Turn off debugging notification
4. close file and databse connections
5. unnessary loop needs to breaked. unsetting memories after usages of variable and object.
6. Use single quote rather double quote
7. use identify operator ===
8. use proper string function
9. calculate only once
10. Pass reference to the function to use the veriable outside the function
11. Reduce number of hits to the database
12. Use intermidate caching technology rather processing same thing again
13. Use derived methods instead of base methods in class
14. use json rather XML for data interchange
15. use isset() always rather using variables directly