I think, magic dosbox has more optimizations then desktop dosbox. Big difference is caused by cpu settings. Cpu power plan is different on tablet and on desktop pc. Or nvidia shield tv (which has not battery and is still connected to power) and shield tablet which optimizes cpu usage in runtime.
As was said in benchmark thread, switching to governor gains more stable cpu speed. And in expert settings you can set cycles=max 120%
Btw, can you help me with controls in that game? How can I get car moving?