The initial release of floats and longs for the Hopper Minimal Runtime was almost entirely written in Hopper.
Recently, compact APIs for float and long were created in 6502 assembly: huge performance gains with a small increase in the ROM size (still under 16K).
Hopper releases on GitHub:
github.com/sillycowvalley/Hop...
NRL BASIC benchmark times:
docs.google.com/spreadsheets/...
Noel's Retro Lab:
noelsretrolab.com/