ETHlargement effect is interesting only for the ETH or for any algorithm that requires fast memory
That is right. I tried with ZEC mining. There is no difference.
Okay, real talk.
ZEC isn't memory bandwidth dependent - not really, not like ETHash. It's compute dependent (and latency bound), so ETHlargement won't be working for this. And there's a reason for that.
What you'll need is EQUILargement. Coming soon.