so it wont have any effect on the speed on the emulator ?
It shouldn't have any effect on the speed while the emulator is running, because in Android each frame is in its own separate Activity. Only one is active and using the CPU and screen at a time (unlike windows which stack on top of each other). It will of course use some memory for the static components (images, strings, etc), but that will be minimal and will have no effect on speed. Emulation speed is affected mainly by processor, screen, and audio hardware usage, because the RAM is fixed, So regardless of how much memory your device has, the emulator uses a fixed amount (it could crash if the device runs out of memory, but it won't slow down). There could be some slow-down in the transitions (going from the menu to the game and vice-versa), but compared to how long it takes to resume the ROM anyway, I doubt it will be even noticeable.