I would do the first one because it's cleaner and more logical.
Code 1
PHP Code:
if ( all of these things are true )
do this stuff
Code 2
PHP Code:
if ( all of these things are true )
exit
do this stuff
Sometimes code 2 makes sense depending on what kind of stuff is going on. But for a basic 2-3 line function, definitely code #1. There is no better from a performance perspective, it's really about taste.
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