Using mouse.target and tool.activated causing massive lag?

Right now I'm in the process of trying to recreate a btools script. I am starting on the delete tool and it is all working perfectly except, that when you try to use it in an area with no parts, it causes massive amounts of lag. When you use the tool for the first time, there seems to be little lag but after you use it a bit then it starts to break. Does anyone know what I can do to stop this from lagging out completely. Here is the script that is causing the lag:

local db = true
local tool = script.Parent
local mouse = game.Players.LocalPlayer:GetMouse()
local cursel = Instance.new("SelectionBox", workspace)
tool.Equipped:Connect(function(mouse)
    mouse.Move:Connect(function()
        cursel.Adornee = mouse.Target
        cursel.Color = BrickColor.Red()
        if db == true then
            if cursel.Adornee ~= nil then
                tool.Activated:Connect(function()
                    local target = mouse.Target
                    cursel.Adornee:Destroy()
                    cursel.Adornee = nil
                    print("e")
                    db = false
                    wait(0.1)
                    db = true

                end)
            end

        end
    end)    
end)


tool.Unequipped:Connect(function()
    cursel.Adornee = nil
end)