A quick performance test comparing closures and regular functions in Lua

benchmark.lua

local function benchmark(func, name, times, ...)
    name = name or "<anonymous>"
    times = times or 100000

    io.write(name, " --> ")
    io.flush()

    local time_start = os.clock()

    for i = 1, times do
        func(...)
    end

    local time_finish = os.clock()

    print(string.format(
        "took %.03fs",
        time_finish - time_start
    ))
end

local debug_env_before = function(env) end
local debug_env_after = function(env) end
local env_shared = {}
local func_shared = function(env)
    local result = 1

    for i = 1, 100 do
        result = result * i
    end

    return result
end

do
    local exe_func
    exe_func = function(func, env)
        return (function(_arg_0, ...)
            local ok = _arg_0
            if ok then
                return ...
            else
                return --os.exit(1)
            end
        end)(xpcall(function()
            debug_env_before(env)
            func(env)
            return debug_env_after(env)
        end, function(ex)
            error(ex)
            return ex
        end))
    end

    benchmark(exe_func, "Without stub")
end


do
    local __exe_func__stub_0 = function(_arg_0, ...)
        local ok = _arg_0
        if ok then
            return ...
        else
            return --os.exit(1)
        end
    end
    local __exe_func__stub_1 = function(env)
        debug_env_before(env)
        func(env)
        return debug_env_after(env)
    end
    local __exe_func__stub_2 = function(ex)
        error(ex)
        return ex
    end
    local exe_func
    exe_func = function(func, env)
        return __exe_func__stub_0(xpcall(__exe_func__stub_1, __exe_func__stub_2, env))
    end

    benchmark(exe_func, "With stub")
end

benchmark_2.lua

local function benchmark(name, func, ...)
    name = name or "<anonymous>"

    io.write(name, " --> ")
    io.flush()

    local time_start = os.clock()

    for i = 1, 1000000 do
        func(...)
    end

    local time_finish = os.clock()

    print(string.format(
        "took %.03fs",
        time_finish - time_start
    ))
end

local function test_func(operation)
    local result = 1

    for i = 1, 100 do
        result = operation(result, i)
    end

    return result
end

benchmark("Without capture", test_func, function(acc, i)
    return acc * i
end)

benchmark("With capture", function()
    test_func(function(acc, i)
        return acc * i
    end)
end)

--[===[
With Lua5.1:
Without capture --> took 2.705s
With capture --> took 2.872s

With Lua5.2:
Without capture --> took 2.718s
With capture --> took 2.725s

With Lua5.3:
Without capture --> took 2.368s
With capture --> took 2.413s

With Lua5.4:
Without capture --> took 2.292s
With capture --> took 2.314s

With LuaJIT:
Without capture --> took 0.094s
With capture --> took 0.136s
--]===]

test.zsh

for lua in {5.1,5.2,5.3,5.4,jit}; do
    echo "With Lua${lua:u}:"
    "lua${lua}" ./benchmark.lua
    echo
done