Well, you are using transient flow simulation which takes lot more time than steady state flow simulation. You can run steady flow simulation for this case for fast convergence.
The computing time depends on the simulation settings, in case of transient sim. the computing times in general are very long (depending on the mesh size, end time etc). Use transient only if it is required by the problem, in most of the cases steady state sim. is fine.
Always check the solver log, if the see anything abnormal e.g high values for the fields, divergence, stop the simulation. Use maximum simulation time option to avoid burning your core hours in case of divergence.