Still useful in the sense that he teaches how to do profiling right: measure, measure, and measure. Don't just jump to attack the code without profiling, try to

Still useful in the sense that he teaches how to do profiling right: measure, measure, and measure. Don't just jump to attack the code without profiling, try to reason about the code, try to reason about the algorithms and data structures, and only at the end go for "low level performance tricks" (as in writing everything in assembly). It's an entertaining read, mostly, but you'll surely don't get much from the 386, 486 and Pentium quirks (and cycle counting) to extract the last drop of performance, other that "back in the old days, Pentium would issue 2 instructions at the same time given a very particular set of conditions". But again, as he does focus on analyzing the problem at large, finding the correct algorithm and data structure, it's still useful.