(Sorry, English)
1802 emulation takes more resources because this device is emulated at a lower level than for example 68000. It will take a lot of steps to emulate 1 single opcode. https://github.com/mamedev/mame/blob...osmac.cpp#L638

I don't think the sensorboard device emulation is that slow. When I was programming it, I tested before-and-after emulation speed and all is good under normal circumstances, certainly not 50% difference. Almost all chesscomputers read the sensors once every few milliseconds, usually during each interrupt routine. However, the Mephisto III connects the chessboard to the 1802 EF1 pin. On emulation, this pin is polled at every opcode. So at 100MHz, it will check the chessboard sensors around 500,000 times per second.