Virtualization and on-demand computing are giving companies new reasons to worry about code efficiency.

Once upon a time, lousy coding didn’t matter. Coder Joel and I could write the same app, and while mine might have consumed 50 percent of the machine’s CPU whereas his could have consumed a mere 10 percent, this wasn’t a big deal. We both paid for our computer, rackspace, bandwidth, and power.

Joel’s code wasn’t measurably “better” than mine (or vice-versa) as long as the apps were the same to the end user. Any advantages were hidden by the step function of physical hardware: Computing costs didn’t grow linearly with the amount of processing consumed.

Modern applications, however, are changing in several important ways:

Continue at source(Alistair Croll, Earth2Tech.net)