Unladen Swallow
Unladen Swallow was an optimization branch of CPython, the reference implementation of the Python programming language, which incorporated a just-in-time compiler built using LLVM into CPython's virtual machine. Like many things regarding Python (and the name "Python" itself), "Unladen Swallow" is a Monty Python reference, specifically to the joke about the airspeed velocity of unladen swallows in Monty Python and the Holy Grail.