Pathological example to show that due to upvalue copying locals can in fact be slightly slower than globals (environmentals)

slowlocals.lua

local vars = {}
for i = 1, 50 do table.insert(vars, ("v%d"):format(i)) end
local all_vars, all_vals = table.concat(vars, ", "), "1" ..  (", 2"):rep(#vars - 1)
local pathological_code = ([[
local %s = %s
return function(get_all)
	if get_all then return %s end
	return v1
end
]]):format(all_vars, all_vals, all_vars)
local pathological_chunk = assert(loadstring(pathological_code))
setfenv(pathological_chunk, {})
local pathological_func = pathological_chunk()
local sane_code = ([[
%s = %s
return function(get_all)
	if get_all then return %s end
	return v1
end
]]):format(all_vars, all_vals, all_vars)
local sane_chunk = assert(loadstring(sane_code))
setfenv(sane_chunk, {})
local sane_func = sane_chunk()

local t = os.clock()
for _ = 1, 1e9 do
	pathological_func()
end
print("locals", os.clock() - t)

t = os.clock()
for _ = 1, 1e9 do
	sane_func()
end
print("envs", os.clock() - t)