Some of the best technical writing I've read lately (and I'll preface this recommendation by saying I've been doing perf for 20 years and never seen datetime being really hot on a profile): there's this autistic motherfucker whose hobby is micro-optimizing date functions and writing about it. It's fucking amazing. Some people go to orgies and shit on their spare time but this being of pure light has got a whole series of posts where he dives deep into a different date function, all the way down to assembly, with genuinely insane algorithmic approaches. My favorite one is where he comes up with a new way to compute weekday from an epoch by abusing the fact that 7 (the number of days in a week) is a Mersenne prime. The performance work is incredibly thorough, providing and benchmarking different implementations of the same techniques for both throughput and latency (something you rarely see in micro-optimizations).