Lua - slow bytcode

Question

i have 3 files x.lua, y.lua and main.lua. These files doing some mathematics operations (increment and decrement number). When i run the command

lua main.lua

is much faster than

luac -o main.luac -s x.lua y.lua main.lua

Please can you help me why is bytecode slower?

• Doub: We need examples files that show the problem.

Answer 1

I'm guessing that main.lua does dofile("x.lua") or require"x" and the same for y.lua.

In that case, the second form runs x.lua and y.lua twice.

Answer 2

They are very different operations:

1. lua main.lua: this does
   • reads 3 files,
   • compiles them to bytecode in memory and
   • executes a subset of their bytecode;
2. luac -o main.luac -s x.lua y.lua main.lua: this does:
   • reads 3 files (the 2 read by main are not read since main is not executed),
   • compiles them to bytecode in memory, then
   • saves three of them to one file on disk.

Writing a file (operation 2) is a slow operation, involving disk access, dumping memory chunks etc; it will be significantly slower than executing some bytecode (operation 1), unless latter is compute intensive.

• Sallomon: Thank you, and please how can i make one bytecode from 3 other files without lost speed
• Oliver: @lhf Ah yes, because the 2 other reads only occur as part of the execution. Updated.