[amadio]

I was just taking a look and couldn't help but notice the switch statement for your operator[], which likely causes a lot of unnecessary bad speculation at runtime:

https://github.com/RandyGaul/cute_headers/blob/755849fc2819d...

I fixed this exact problem in a highly used library in high energy physics:

https://gitlab.cern.ch/CLHEP/CLHEP/-/commit/5f20daf0cae91179...

Many believe the C++ compiler will magically optimize the switch away, but in some cases, like the example above for CLHEP, it doesn't happen, so you end up with bad performance.

[amadio]

Since you left this "optimize me" comment here:

https://github.com/RandyGaul/cute_headers/blob/755849fc2819d...

See an optimized quaternion multiplication implementation in SSE by me here:

https://stackoverflow.com/questions/18542894/how-to-multiply...