How to Get A Part Follow Player With No Lag?

The following script uses rocket propulsion to fire a projectile that follows the player by using brick welded above the player as a target. Keep in mind you might have to change the MaxSpeed and MaxThrust values of the rocket depending on the outcome you want and the weight of the part.

local p = Instance.new("Part")
p.FormFactor = "Custom"
p.BottomSurface = "Smooth"
p.TopSurface = "Smooth"
p.Size = Vector3.new(3,3,3)
local c = Instance.new("RocketPropulsion",p)
c.Name = "rocket"



game.Players.PlayerAdded:connect(function(player)
    player.Character:connect(function(character)
        local u = p:Clone()
        u.Size = Vector3.new(0,0,0)
        u.Cancollide = false
        u.Transparency = 1
        u.Parent = character
        local w = Instance.new("Weld",character.Torso)
        w.Part0 = character.Torso
        w.Part1 = u
        w.C0 = CFrame.new(0,9,0)
        local clone = p:Clone()
        p.CFrame = CFrame.new(character.Torso.Position + Vector3.new(0,8.5,0)
        p.Parent = workspace
        p.rocket:fire()
    end
end)

local plr = game.Players.LocalPlayer
local char = plr.Character or plr:CharacterAdded:wait()

while wait() do
local part = script.Parent
local t = char.Torso

part.Position = t.Position

end)