  OCTO-TIGER is an astrophysics code to simulate the evolution of
self-gravitating and rotat-ing systems of arbitrary geometry based on the fast
multipole method, using adaptive mesh refinement. OCTO-TIGER is currently
optimised to simulate the merger of well-resolved stars that can be
approximated by barotropic structures, such as white dwarfs or main sequence
stars. The gravity solver conserves angular momentum to machine precision,
thanks to a correction algorithm. This code uses HPX parallelization, allowing
the overlap of work and communication and leading to excellent scaling
properties, allowing for the computation of large problems in reasonable
wall-clock times. In this paper, we investigate the code performance and
precision by running benchmarking tests. These include simple problems, such as
the Sod shock tube, as well as sophisticated, full, white-dwarf binary
simulations. Results are compared to analytic solutions, when known, and to
other grid based codes such as FLASH. We also compute the interaction between
two white dwarfs from the early mass transfer through to the merger and compare
with past simulations of similar systems. We measure OCTO-TIGERs scaling
properties up to a core count of 80,000, showing excellent performance for
large problems. Finally, we outline the current and planned areas of
development aimed at tackling a number of physical phenomena connected to
observations of transients.
