Re^2: The Rules of Optimization Club

[tobyink]

This viewpoint completely neglects that the programmer's time is paid for once; but the time user's and customer's spend waiting for code to complete, is repeated over and over. And they pay the bills.

That very much depends on the task at hand. Consider this: on a database there are 10,000 or so payment schedules recorded for £3 every 4 months, but it turns out this was a systematic data import error, and it should be £4 every 3 months.

Given a choice between:

• Programmer spends 2 hours writing a script that fixes problem at a rate of one payment schedule per second; and
• Programmer spends 4 hours writing a script that fixes problem at a rate five payment schedules per second.

Then chances are that the first solution would be preferred. OK, so the script is going to take close to three hours to run, but it's a one-off fix, and nobody has to stand over it while it's running.

There are cases where the developer's time is more precious than the performance of the program. And there are cases where the performance of the program is everything. Most, of course, are somewhere in between.

[BrowserUk]

but it's a one-off fix, and nobody has to stand over it while it's running.

Exactly! One off and no user waiting. Unimportant, and beyond the scope of the remit.

Contrast with millions of people every hour of every day, waiting a couple of extra seconds for their ging/gang/boogle/yoohoo/facespace/mybook/tweedle/amabay/tescutters interactions.

Excess cycles consumed by one customer are lost to others waiting. IO-bound doesn't mean either non-urgent or non-critical.

Even for far smaller scale businesses, the loss of individual customers to impatience with sluggish backends and overindulgent, pretty frontends can be critical to your bottom line.As the world gets smaller and the choices of places to shop get ever wider, efficiency is critical to first establishing and then keeping a customer base.

Web pages that fail to respond within 10 seconds; or that aren't ready to accept input with 3; just don't get a chance to sell me anything, much less advertise to me -- by then I've moved on to the next hit on the search engine list.

Leaving optimisation as an after thought, rather than building it in and measuring it as you design and develop your code is like building a shop with narrow, difficult to open doors and not switching the lights on.