Anybody ever benchmarked lua string ops?

Based on my (very) light reading about the Lua implementation, I'd guess that Lua string operations are roughly the same cost as Java string operations. There are two components to the cost: doing the byte manipulations, and the amortized cost of garbage-collecting the strings later.  Unlike Java, Lua needs to hash each string into a global string table, but the incremental cost of that is likely smaller than you think for many apps, since tests for equality take a single instruction, and the hashing can reduce additional storage allocations.   Also, I'd guess that the Lua garbage collector is not as efficient as a modern Java GC, but that's just an educated guess.