Okay, here is a summary of the provided video:

Linus Torvalds explains that he doesn't do a lot of programming anymore, he merges other people's code. He states that he is currently in charge of overseeing the Linux git history. He looks at the kind of code he's changed recently, and made sure our file path lookup takes as few cache misses as possible. All the code is in C, but it's optimized at the level where he worries about single instructions and especially single cache misses. Torvalds says, "And I love doing that because that's it's completely I mean, to some degree people say you should not micro-optimize, but if what you love is micro-optimization, that's what you should do."