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kotlinlang

I recall seeing a couple of issues regarding Protobuf and the fact it's not as performant as it should be, tho maybe I've mis-interpreted the problem.
Did you consider testing out <https://github.com/apache/fory>?

Not yet. Because Kotlin serializes data in protobuf in both JARs and Klibs, we need to be able to read and write proto for a long time, and cannot simply change the binary format. Instead we want to just optimize the protobuf (de)serialization.
But in the future, at least for Klibs, we will consider doing so (switching the format). The speed won't be the first priority though, rather the size and compatibility.