PHP Performance of !isset() vs === null

Question

I'm aware of the benchmarks for isset() vs empty(), but I have code I need to execute only when the argument is null. This is in a function that executes many times so I'd like to optimize it.

I know that isset() is faster than empty(), but what about !isset() vs. === null? I know that the variable will exist, so I only need to test it against null.

I'm thinking of the possible penalty for the ! operator.

Answer 1

I felt lazy asking someone else to benchmark this, so I tried a million iterations.

The difference is trivial, so !isset() is a better option since === null would throw an error if the variable was ever undefined.

One Million iterations:

   !isset()  .1118
   === null  .1046

BTW, there is an (also trivial) penalty for the ! operator.

   isset()  .1118
   !isset() .1203