There were some good comments that post's thread [2], including from burntsushi of ripgrep.
Need to figure out what area they excel in - there is no one search that is the best for all types of data and pattern/search length.
Low level: memchr [1];
Medium level: Regex (Rust crate) [2];
High level: ripgrep [3].
Other names to look out for are the previously aforementioned Wojciech Muła, as well as Daniel Lemire (of simdjson [4][5]). Not SIMD-specific, but Data-Oriented Design can be a big help in terms of thinking about SIMD and cache-friendly data layout (as well as trimming down the work that the computer needs to do, generally). I've talked that to death, so I'll just link those comments here [6].
1. https://docs.rs/memchr/latest/memchr/
2. https://docs.rs/regex/latest/regex/
3. https://github.com/burntsushi/ripgrep
4. https://www.youtube.com/watch?v=wlvKAT7SZIQ
5. https://arxiv.org/pdf/1902.08318
6. https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
https://gitlab.com/bztsrc/fast_memcasemem
See the performance comparison in the README, it's about 6 times faster than libc.
(*) - full UTF-8 support, but only works for UNICODE codepoints where the UTF-8 encoding lengths are the same for lowercase and uppercase. There are only 27 out of 40576 pairs which aren't handled (listed in the README).
This very same property got me to post this [1], which sent me down the rabbithole of learning about Unicode in earnest and building my Unicode tool. Which may have an initial release some time this millennia... maybe.
Sometimes there's an offset (like with Latin, +/- 32), sometimes lowercase and uppercase is interleaved (eg. Latin extended), and sometimes they are in totally different blocks simply because they forgot to add both letter cases at once... (the distance of the codepoints affects UTF-8 encoding difference the most).
I've also paid attention to optimize the most common case where both UTF-8 encodings' first bytes are the same (that's 40508 pairs out of 40549). But no escape, it must handle the remaining 41 pairs specially in a slower code path, which would not be needed at all should UNICODE guys did their homework better.
Lots to read about here for those interested (and that's without getting into `Casefold`, `NFKC_Casefold`, simple vs complex case mappings, the CLDR, etc.):
https://www.unicode.org/versions/Unicode17.0.0/core-spec/cha...