on_chatmessage wraps

chatwrap.lua

local t
minetest.register_on_chat_message(function()
	t = minetest.get_us_time()
end)
for _ = 1,1000 do
	minetest.register_on_chat_message(function() end)
end
minetest.register_on_chat_message(function()
	print("direct: " .. minetest.get_us_time() - t .. " ms")
end)

local ocs = {}
local function ocw(func)
	ocs[#ocs + 1] = func
end
minetest.register_on_chat_message(function()
	t = minetest.get_us_time()
end)
minetest.register_on_chat_message(function(name, message)
	for i = 1,#ocs do
		if ocs[i](name, message) then
			return
		end
	end
end)
for _ = 1,1000 do
	ocw(function() end)
end
minetest.register_on_chat_message(function()
	print("wrap: " .. minetest.get_us_time() - t .. " ms")
end)

results
Note that ms should be µs there.