10. WHERE clauses - In a WHERE clause, the various operators used directly affect how fast a query can run. Here are the conditional operators used in the WHERE clause, ordered by their performance.
=, >, =, <=, , !=, !>, !<
for details, refer to the article: http://msdn.microsoft.com/en-us/library/ms190276.aspx
The article you've linked to does not support your point, as far as I can see. That article addresses operator precedence, not performance. Your point may be correct for all I know, but that article doesn't address it one way or the other.
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a haiku...
NULL is not zero
NULL is not an empty string
NULL is the unknown