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On 03/01/2014 20.37, Tom N Harris wrote:

table.concat and/or the C-level luaL_Buffer can be useful to reduce
>memory usage in these cases.

The VM concat instruction is very efficient so a chained .. is no worse than
table.concat. Where you get in trouble is building a string piecemeal in a
loop.
Yes, I am aware that table.concat and luaL_Buffer are not equivalent (that's why I wrote "and/or": convenience depends on the operation). 


    function GCAndShow(prompt)
      local before = collectgarbage "count"
      collectgarbage"collect"
      local after = collectgarbage "count"
      io.write(string.format('%s: %.1fKiB (%.1fKiB garbage)\n',
                             prompt, after, before-after))
    end
By the way, I noticed that calling collectgarbage() only once, with 'collect' implied by default, does not always seem to perform a complete collection in Lua 5.1. 

--
  Enrico