CPU's get faster - we make slower code - we need faster CPU's to run or slower code - now we have even faster CPU's so we are satisfied with even slower code - now we need faster CPU's again....get my point???
The thing is, it's not all about performance. I don't know why young programmers are so wound up about clock cycles and such. If your app runs acceptably on your target platform, that's enough. Faster processors allow you to use higher and higher levels of abstraction and layers of libraries (like Blitz products).
Code from the old days was highly optimized, yes. It was also hard to read and almost impossible to maintain.
Bottom line ... hacking in assembler sucks. Nobody wants to do it anymore.