How to change the speed of how fast my part is going(CFrame)?

local RunService = game:GetService("RunService")
local part = game.workspace:WaitForChild("Start")
local part1 = game.workspace:WaitForChild("Finish")

local PART1_POS = part1.position
local PART_POS = part.position
local DURATION = 5


RunService.RenderStepped:Connect(function()
	local deg = 0*(wait(10) % DURATION)/ DURATION
	part.CFrame = CFrame.new(PART1_POS) * CFrame.Angles(0,0,(deg),0) * CFrame.new(PART_POS)
end)

That is what I have so far, but whenever i try it the part moves instantly, it does not move smoothly to the other part? How do you fix this?

The best way to do this would be to use TweenService.

Essentially, use the TweenInfo.new function to declare the speed of the tween.

Use the TweenService:Create() method to create the tween.

And finally, use the Play function to play the tween.

local TweenService = game:GetService("TweenService")
local part = workspace:WaitForChild("Start")
local part1 = workspace:WaitForChild("Finish")
local tweenInfo = TweenInfo.new(5) --5 Seconds
local goal = {};
goal.CFrame = part1.CFrame; --Make the goal's CF part1's CF
 
local tween = TweenService:Create(part, tweenInfo, goal)
tween:Play()