Worker.MaximumCoreCount

From Xojo Documentation

Property (As Integer )
aWorker.MaximumCoreCount = newIntegerValue
or
IntegerValue = aWorker.MaximumCoreCount

New in 2020r2

Supported on Desktop.

The maximum number of cores to use. Regardless of the percent, this is the most CPU cores that will be used. This should be 1 or greater.