Low performance usage, Low fps?

[[RDSR] Raphi]

Just a guess, run the p3d executable at higher priority and see if anything changes. Have a look at your CPU usage by core instead of all cores; it should give you an answer about whether the cpu is giving its best or just "idling". I'm sure the game uses only one or two cpu cores, therefore creating a bottleneck hence why your gpu's at 15%