I recently asked a question on Stack Overflow to find out why isset() was faster than strlen()isset() was faster than strlen() in PHP. This raised questions around the importance of readable code and whether performance improvements of micro-seconds in code were worth even considering.
My father is a retired programmer, and I showed him the responses. He was absolutely certain that if a coder does not consider performance in their code even at the micro level, they are not good programmers.
I'm not so sure - perhaps the increase in computing power means we no longer have to consider these kind of micro-performance improvements? Perhaps this kind of considering is up to the people who write the actual language code? (of PHP in the above case).
The environmental factors could be important - the Internet consumes 10% of the world's energy. I wonder how wasteful a few micro-seconds of code is when replicated trillions of times on millions of websites?
I'd like to know answers preferably based on facts about programming.
Is micro-optimisation important when coding?
My personal summary of 25 answers, thanks to all.
Sometimes we need to really worry about micro-optimisations, but only in very rare circumstances. Reliability and readability are far more important in the majority of cases. However, considering micro-optimisation from time to time doesn't hurt. A basic understanding can help us not to make obvious bad choices when coding such as
if (expensiveFunction() || counter < X)
Should be
if (counter < X || expensiveFunction())
(Example from @zidarsk8) This could be an inexpensive function and therefore changing the code would be micro-optimisation. But, with a basic understanding, you would not have to, because you would write it correctly in the first place.
