Amdahl's law, 55 years later

This is where the 'intrinsic' pseudo-functions that Intel created for compilers greatly simplifies the code so you don't need to break out raw assembly and can let the compiler still deal with register usage and inter-mix its code with yours.

https://www.intel.com/content/www/us/en/docs/intrinsics-g...

For a simple but sufficient example of the escaping-strings idea, and how you can POPCNT the mask used for VPCOMPRESS to get the byte-count written https://lemire.me/blog/2022/09/14/escaping-strings-faster... is a pretty decent point of reference.