De lagging a for loop with an if statement?

So I have a for loop that checks to see if the variable 'calloff' is true, if it's true then it stops the for loop, how would I make it so it doesn't instance abuse?

local finished = false
local calloff = false

coroutine.wrap(function()
		for racewait = 175, 0, -1 do
		wait(1)
		if calloff == false then
			game.Workspace.StartingLine.Timer.SurfaceGui.Time.Text = "Race time: "..racewait
				for _, Player in pairs(game.Players:GetChildren()) do
        			if Player:IsA("Player") then
            			Player.PlayerGui.MainGui.TimeFrame.Timer.Text = "Race time: "..racewait
        			end
				end
			else
		end
	end
finished = true
end)() 

game.Workspace.Positions.Last.Changed:connect(function()
	if game.Workspace.Positions.Last == true then
		calloff = true
		wait(1)
		calloff = false
	else
		calloff = false
	end
end)