First create a sprite make it a circle fill it in with black or any color.

Then create two object one called object0 and one called paint and another called system.

Make all the objects except system have the black circle as the sprite.

For system do this

Create Event

xx=mouse_x
yy=mouse_y


Step Event

if instance_number(object0)>0 then instance_destroy()


Global left button.

instance_create(xx,yy,object0)

----------------------------------
Object 0

Create event

xx=mouse_x
yy=mouse_y


step event

if instance_number(object0)>1 then {instance_change(paint,false)}


glob left button

instance_create(xx,yy,object0)

-----------------------------

Then put object system in your room and it should work perfectly lag free.

Give credit to me if you use this.
I also hope people learn from this.