But i did it before with other games, to some degree. Performance is in architecture not so much language, you can make it in asm and still underperform.
And about languages:
Kotlin = Java -> BUT! Its less verbose and has really nice utils and you can get up and running really fast, at times it can be slower than java since it has overhead runtime checks.
Go -> is a machine language with a GC with sweeps under 0.5 ms.
Rust -> is basically C but with an awesome compiler and a rich toolkit. (Voted most loved language)
I'm not saying imma complete a mmo server by myself, i'll most probably hit a limit where I can't do it alone anymore. That's why my scope is little, and will be like interpreting of static data that we already have in l2off and l2j, combat & a completeness of client features, I'm not gonna do quests, epic bosses or elaborate systems, unless someone else wants to make up a team.
Also take my veteran advice, dealing with a small scale server != designing architectures for finleap companies with 300+ people & collaborators & several banking service providers. And i really wanna get proficient with go thats why this motivates me, if it's gonna help someone fine, if not I learn more go, so i'll be happy at the end.
Thanks for the concern tho :*