TestParallelLua.lua

local UserInputService = game:GetService("UserInputService")
local RunService = game:GetService("RunService")

local printRender = false

UserInputService.InputBegan:ConnectParallel(function(inputObject)
	print("Running parallel (ConnectParallel) ", tick())
	printRender = true
end)

UserInputService.InputBegan:Connect(function(inputObject)
	print("Running synchronious (Parallel)", tick())
	printRender = true
end)

UserInputService.InputBegan:ConnectParallel(function(inputObject)
	printRender = true
	task.synchronize()
	printRender = true
	print("Running synchronious (ConnectParallel, task.synchronize())", tick())
end)

UserInputService.InputBegan:Connect(function(inputObject)
	printRender = true
	task.desynchronize()
	printRender = true
	print("Running parallel (task.desynchronize())", tick())
end)

RunService.RenderStepped:Connect(function()
	if printRender then
		printRender = false
		print("RenderStepped occured", tick())
	end
end)