Forti SandBox VM (Files/Hour)

For  Forti SandBox VM  (Files/Hour)  , This parameter increases when Model Increases

For Example ,  FSA-1000F  provides  120 VM Sandboxing Throughput (Files/Hour)  while  FSA-1000F provides  280 VM Sandboxing Throughput (Files/Hour) .

Any Explanation why VM can handel more Files with Higher Model ?

Also how come VM handels 120 Files/Hour  while  average for file Sandboxing analysis is 3-4 Min (  so seems practically only 20-15  Files can be SandBoxed by Single VM per hour ) ?