Peter "Durante" Thoman—creator of DSFix for Dark Souls and the Generic Down-Sampling Tool—has posted an article at PC Gamer about the realities of game optimization. This isn't the first time Durante has written for the site, and in your scribe's opinion, he writes frankly and clearly about PC gaming in a way few people do.
With every new major PC game release, there will always be some users that complain about the game's "optimization." As Durante says, these complaints are usually just shorthand for "this game doesn't run well on my PC." His write-up seeks to shed light on exactly what "optimization" means, and why it isn't simply a matter of technical skill. Durante spoke with Croatian game developers Croteam (of Serious Sam fame) and Polish localization house QLOC to gain their insights on game optimization.
The article is more of an overview rather than an in-depth examination, and as a result it doesn't go into a lot of detail. Durante sheds light on some of the most computationally expensive graphics settings we find in games, and then goes on to talk about how many "optimization" issues are related to surprisingly non-technical things. He also mentions how users can cause "optimization" issues of their own with careless option-twiddling. Definitely worth a read.