> I much prefer it to writing intrinsics in C (and the results are just as good). It's an interactive, exploratory, coding: I write small modular functions, SBCL compiles them on the fly, I glue them together with high-level language constructs.

Same here, but in Julia instead. Sometimes I drop down to LLVM intrinsics (e.g. to force lop3.lut on GPUs).