Optimize jsonrpc request throughput

[edubart]

Context

Currently these are some numbers of very lightweight advance requests (without forks) made through local/jsonrpc/grpc machines:

local 2819.05 req/s
jsonrpc 491.62 req/s
grpc 69.71 req/s

Local is way faster than jsonrpc, jsonrpc adds the overhead of:

• Networking
• Establishing a new connection for every machine method call
• JSON serialization/deserialization

Possible solutions

We can optimize jsonrpc requests during a remote machine session by using keep alive connections, if that is not enough, we should also investigate if there are simple ways to optimize the serialization or networking.