The banana and the Raspberry have something in common. They are both zeros concerning game emulation.
The 0,2Ghz in difference for speed will not save you, as the memory of both is limited at 512MB, thats nothing for 4 core cpu. So, only option for handheld is to find something more powerful, as example the cm3 (PI3 without interface circuits) is fine. You have several case+board adaption to the Cm3. I have a Freeplay GBA in an GBA Advance spare case. Enough to run games as quake in dos emulation. Problem is often projects with high resolution screens, up to 800x600. This will never work, as the size take down the rest of the memory, and 4 or 16 cores are not important anymore, because of the memory shortage.
To switch from PI3 to Cm3, there is without the interface problematic, just an overlay to change in the soft,
add boot loader bcm2710-rpi-cm3.dtb to bcm2710-rpi-3-b.dtb if not already present.
You can find the project on my german site, in Recalbox you have no pictures anymore as I blocked their access to my server. 🙂 https://www.antik-automaten.de/wbb2/thread.php?threadid=2605