[DJMaze]

#8: Use full paths in includes and requires, less time spent on resolving the OS paths.

This is wrong. In PHP5 when you use full paths each directory gets checked for permissions.
It makes any disk access function 4 times slower then in PHP 4 (per request around 0.0016 seconds).

#9: $_SERVER[’REQUEST_TIME’]
This is inaccurate and does not contain the script execution but the REQUEST

#17 $row[’id’] is 7 times faster than $row[id]
That's because $row[id] is bad code. Use error_reporting(E_ALL) and you will notice that PHP tries to find a constant named id.

The rest is rather true, yet some points sound like being the same as a previous point.