Q. Is there any difference for Lua whether it gets 1 million strings via the network interface, or whether it constructs those strings itself? Is the slow part not the internalization and that would be the same for both methods of acquiring the string? (2016)
A. In the 1M transactions benchmark, Lua is not involved at all.
Perhaps, there is a misconception about Tarantool: it is a database written in C and C++. It embeds Lua for extension, but it does not use Lua at all for core database features, like transactions or replication.