C3 RUNTIME: 26 fps and 1.8% CPU
If you look in the profiler tabs you can get much more detailed information about both the CPU and GPU usage.
However given the low CPU usage and low FPS, I would guess you have an older device that's in the few % of systems that get kicked down to software rendering. The C3 runtime only uses WebGL so presumably with the C2 runtime you're getting canvas2d rendering only (which is possibly hardware accelerated, since it has lesser requirements). Try installing any software updates or updating the graphics driver. Most modern devices should be fine. Assuming you're using Chrome you can get more detailed information by visiting chrome://gpu in the address bar.
Also the framerate shouldn't affect the speed anything happens if you correctly use delta-time.