I don’t know why it’s fast, but it is. The compiler must be doing something fancy. When I try on a super simple cutdown, using ntuple is the same as ...,, but inside of my function it works great!
The syntax is so obtuse that VSCode highlights it as a possible error, though =P.
@lmiq I’m using fun(ntuple(i->vec[indices[k][i]],3));
Thanks again, everyone!