sudomod

I hope this is the right place to ask, sorry if not, I'm just new to this and excited

Two days ago I got my first pi ever, pi zero, with the full intent of building a gbz (technically freeplay zero, but that's because I like the gba shell better). I was a bit hesitant buying the zero, because I read contradicting performance reports and so decided to buy only the board at first to test it out.
It took me a while to get the grips and have games and bios loaded but I have to admit, the zero had trouble playing mario kart for the snes and Kirby's Adventure for the NES at full speed (I don't have speakers in my computer monitor so I don't know how the sound was). This makes me wonder if the pi zero is actually up for the task of gbz. It's not that I plan on emulating ps1 games, but I hoped for gba emulation since I grew up with it.
On what settings and what kind of games do you run and play on your gbz? I read people overclock the borad but I don't know how and I'm afraid to damage the board.
Should I contact the store and ask to upgrade it to the 3b+ and just go with a regular gb shell instead?

Thanks in advance

I find the pi zero sufficient for the most part. Some games from SNES and GBA I found were not perfect. I have played through minnish cap and megaman zero x series, but not much other GBA experience. But for the most part it's always good enough for the type games I play.

And it's nice and small for portables. You mention the Freeplay zero. You could also look at the Freeplay cm3, which uses the compute module 3, equavalent to a pi 3.