Embedded switches?

[Richmond Mathewson]

I have to use either:

1. A multi-case switch statement with many sub-switch statements inside it,

or

2. A multi-case switch statement with many IF . . . THEN statements 
inside it,

or

3. Many IF . . . THEN statements with many IF . . . THEN statements 
inside them.

Number 3. is obviously going to slow things down a ton!

Should I choose 1. or 2 ?  and why?