I dunno, actually... Given how efficient more recent versions of DOSBox are, if they made a verison that would be wholly native on the ARM-9, I wouldn't be surprised if Arena could be run at 20+ FPS.
There's a DOSBox port available for Nokia N800 which got a 400MHz ARM CPU. It can run about 1500-1800 cycles without sound emulation and about 500-1000 cycles with sound emulation.
Granted, the port is stuck with the normal core, cause noone made a dynamic core for the ARM architecture.