Simulate Early, Simulate Often... In Rhino
There are no settings in Scan&Solve to adjust the processor utilization. The code is only parallelized in the computationally-intensive section where Scan&Solve reports "Building linear system." Even there, processor utilization can depend on MANY factors including processor brand, model, memory size, simulation size, operating system, other program activity, BIOS settings, etc. Your BIOS settings for enabling/disabling hyperthreading MAY make a difference.