How can I make this script run efficiently?

As you can see, you may recognize this script from old zombie models that are instructed to follow you. However, I can't find any way to make this run faster, because if there are too many models using this script, the game runs too slow. I've tried making the loop slower and doesn't work.

local larm = script.Parent:FindFirstChild("Left Arm")
local rarm = script.Parent:FindFirstChild("Right Arm")

function findNearestTorso(pos)
	local list = game.Workspace:children()
	local torso = nil
	local dist = 100
	local temp = nil
	local human = nil
	local temp2 = nil
	for x = 1, #list do
		temp2 = list[x]
		if (temp2.className == "Model") and (temp2 ~= script.Parent) then
			temp = temp2:findFirstChild("Torso")
			human = temp2:findFirstChild("Humanoid")
			local player = game.Players:GetPlayerFromCharacter(temp2)
			if not player and (temp ~= nil) and (human ~= nil) and (human.Health > 0) and human.Parent.Name ~= "Zombie" then
				if (temp.Position - pos).magnitude < dist then
					torso = temp
					dist = (temp.Position - pos).magnitude
				end
				elseif player and (temp ~= nil) and (human ~= nil) and temp.Transparency ~= 1 and (human.Health > 0) and player.TeamColor ~= BrickColor.new("Bright green") then
				if (temp.Position - pos).magnitude < dist then
					torso = temp
					dist = (temp.Position - pos).magnitude
				end
			end
		end
	end
	return torso
end



while true do
	wait(1)
	local target = findNearestTorso(script.Parent.Torso.Position)
	if target ~= nil then
		script.Parent.Humanoid:MoveTo(target.Position, target)
	end
end

If this is in a Local Script, then use game:GetService("RunService").RenderStepped, which runs at 60 times a second. If you are using a Server Script (a regular script) then use game:GetService("RunService").Heartbeat. The server doesn't have access to RenderStepped.