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.