Is it? Checksums are something that I use rather than understand, but the CPU is doing billions of instructions per second these days and the hash only happens once
Do openssl speed sha256 to get the idea how high the latency for a cache hit would be. I see a throughput of ~300MiB/sec. This can be parallelised easily but still we are burning lots of CPU cycles for nothing. Bad for battery life.
https://gist.github.com/nonylene/d08977e8952c83d20d2c5f7cbaf...