Simulation Threads

This number represents your computer's number of CPU's or cores:

  • If your computer supports hyper-threading you will see a higher value.
  • Threads can be adjusted for each scene individually under → Simulation Options > General.

Low CPU Performance?

There are situations where RealFlow uses only a fraction of the available cores and CPU load is just around 10%. This is typically the case with low-resolution fluid simulations:

  • RealFlow requires some time to split the simulation into threads.
  • With just a few thousands of particles it is normally better to reduce the number of threads.
  • The more particles, the better the computer's performance.
  • In simulations with several millions of particles, all cores will be used and CPU load is often 90% and higher.


Another thing you will observe is a performance drop at the beginning of a simulation or between two frames:

  • When a simulation starts RealFlow prepares lots of things and these processes are all single-threaded.
  • Saving simulation data is also single-threaded and hardly uses any CPU power.

More Cores = Better Performance?

With more than 32 threads you will hardly see any performance boosts, because computer systems do not scale linearly and there is always a limit.

Fast HDDs or better: SSDs, together with a decent amount of RAM (32 GB or more), will speed up your simulations though.