Math functions (sine & cosine) latency

I think i found the same problem as you, however, i've found a workaround.

I am using the NIOS II/f core with custom floating point instructions (with also, hardware divide support) and Quartus/NIOSII EDS 10.0 in linux

What i've found is that the linker always uses a generic library libm.a file (for cosf, sinf et al.), no matter what kind of hardware implementation you have.

So what i made was to change the generic libm.a contained in altera/10.0/nios2eds/bin/gnu/H-i686-pc-linux-gnu/nios2-elf/lib file with the libm.a contained at altera/10.0/nios2eds/bin/nios2-gnutools/H-i686-pc-linux-gnu/nios2-elf/lib/mcustom-fpu-cfg=60-2

This has made that a system that was operating at 200Hz jumped to 1100 Hz , so the gain in performance is considerable.

You can always check the objdump to see in the assembler code generated if the code is calling mulsf3 or custom instructions.....