Hi, is this coin mineable on 3GB or 4GB cards these days? And using which miner (for the best speed)? Thanks!
There's a FIRO guide on mining in the OP and here's the link for that:
https://firo.org/guide/how-to-mine-firo.html.
That guide doesn't say anything about minimum VRAM, which I think is a pretty gross omission.
Anyway, 3 or 4 GB cards won't work. The MTP scratchpad itself needs 4 GB and then you needs some for the rest of the program, so the total is about 4.5 GB. If you can find a 5 GB card that should work. 6 GB is plenty.
I recommend the official
https://github.com/firoorg/ccminer as it is open source with no hidden fees. I haven't found a closed miner whose speed increase is worth the fee (and the risk of running untrusted software).