After investigation it is clear that the older Particles Metal DEMO is really more an DEMO, and not usable as bench - because CPU bound limit, very huge cpu loads generating and moving that particles.
From source here : https://github.com/F...alKit-Particles
compiled app : from DOWNLOAD
Screenshoot shows low cpu usage but very high (full) GPU load = i think diff gpus should perform different, compared to the demo below.
6 FPS Nvidia GT 740
18 FPS Nvidia GTX 650