pfsspy automatically detects an installation of numba, which compiles some of the numerical code to speed up pfss calculations. To enable this simply install numba and use pfsspy as normal.
pfsspy has two streamline tracers: a pure python pfsspy.tracing.PythonTracer and a FORTRAN pfsspy.tracing.FortranTracer. The FORTRAN version is significantly faster, using the streamtracer package.