Very recently I had a bit of code that worked. Its job is just to load a database with some fixed-width data from one source, some TSV data from a couple of others, and do a bit of manipulation of that data on the fly. In order to prevent online customers from finding bogus data, the web site that presents that data had to be suspended during the run of the database loader. It wasn't a big deal to suspend the site, as it was only for ~45 seconds per day. The site would lose at most one sale during that time.

Then the dataset grew, the requirements changed, and the thing that once worked just fine required 20 minutes or more to run. 30 sales lost per day was not acceptable to the client. Suddenly, runtime mattered a lot.

Like so much of life, the correct answer is situationally dependent. Performance may or may not matter, but you cannot issue one statement and expect it to fit all cases.

As someone else said, first make it run, then make it run fast. To that I would add, "... if fast is necessary".