$t_{\rm par}$   $t_{\rm grav,1}$   $t_{\rm grav,2}$
  ----- ----------------------------- ----------------------------- -------------------- ---------- --------------- ------------ ------------- ------------ --------------- ------------------ ------------------
  M1             $(1.32)^3$                      $256^3$             $2\times10^{-14}$    $0.0015$   $9\times10^5$     $0.05$         N/A         $40.0$          N/A              N/A                N/A
  M2             $(1.32)^3$                      $256^3$             $2\times10^{-14}$    $0.003$    $2\times10^5$     $0.05$        $0.5$        $40.0$        $20.0$            $20.0$             $33.0$
  H              $(1.32)^3$                      $512^3$             $7\times10^{-16}$    $0.0015$   $9\times10^5$     $0.05$        $0.5$        $40.0$        $32.0$            $35.0$             $37.0$

The first column gives the name of the simulation, while the box size and the grid resolution are given in the following two columns. The next column gives the hyperdiffusivity coefficients. The next two columns give the mean vertical magnetic field and the corresponding plasma-$\beta$. The next column gives the sub-Keplerian velocity difference. The following column shows the particle self-gravity parameter $\tilde{G}$. The last four columns give the total simulation time, the time when particles were released, and the times at which self-gravity was started and self-gravity simulations were stopped. \[t:parameters\]

In [Fig. \[f:timings\]]{} we show timings for a test problem with $512^3$ grid cells and $64\times10^6$ particles. The particles are distributed evenly over the grid, avoiding load balancing challenges described below. We evolve gas and particles for 1000 time-steps, the gas and particles subject to standard shearing box hydrodynamics and two-way drag forces. The lines 