I was able to reproduce the problem you have described.
It seems there is an issue when using operators in a graph which implement a certain method (computeTileStack()).
In this case the parallelisation isn’t working correct.
When using the operator directly, without a graph, the CPU usage is 100%. For me it dropped to 18% when used in a graph.
After specifying the -q option with a value of 120, I got the 100% again. It increases the number of allowed threads to 120.
Maybe you have to play a bit with this value. For me it is 10 * NumCores.
I haven’t tried a graph which contained both, the resample and the BiophysicalOp. It might happen that the resample op suffers from this setting or maybe you might need to set it even higher.
However, this is a bug we have to fix.
Thanks for the valuable report