Use something else rather than Wait()?

So, im doing a script for a logic gate, that the player will be able to choose from delay and hold (i dont know if i will add more later). And the code is the following:

	if FT == true then -- FT is the status of the input (true or false)
		ACTIVE = true -- prevents plr from changing the timer mid activation
		IN.BrickColor = BrickColor.new("Bright blue") -- changes INPUT color
		--wait(TOTALTIME) -- error here!!
		--note: TOTALTIME is in seconds, by multiplying minutes by 60
		OUT.BrickColor = BrickColor.new("Bright blue")
		status[INDEXOUT1] = true
		
	else
		ACTIVE = false -- lets the player change the timer again
		IN.BrickColor = BrickColor.new("Black") -- changes back color
		OUT.BrickColor = BrickColor.new("Black")
		status[INDEXOUT1] = false
	end
	
	

but everytime the script reads wait(TOTALTIME) it will stop everything and wait untill that is done i tried something else like:

while TIME > 0 do
	wait(0.001)
	TIME = TIME - 0.001
end
if TIME <= 0 then
	TIMEOVER = true
else
	TIMEOVER = false
end

but its not decreasing correctly, if there is no wait() it does it instantly. but if there is a wait() it does it super slowly, not on the correct time. I have no idea of how to fix this, if someone could help me i would appreciate it alot!

All the code is being run on the same thread, which is why the loop stops everything else until it is finished. You can run the while loop on a different thread using a coroutine

Perhaps you can also try using the Heartbeat with the Wait function, which will wait for the event to fire, which will be every frame.

coroutine.wrap(function()
	while TIME > 0 do
		game:GetService("RunService").Heartbeat:Wait() 
		TIME = TIME - 0.001
	end
end)()

if TIME <= 0 then
    TIMEOVER = true
else
    TIMEOVER = false
end