Using the lasso much in the same drawing is one thing. Working in 4K is another.
The good news are that you should work in a resolution that is not too demanding for your hardware – and when you at some point want to export your finished animation, you can always just scale up to 4k if that is what your output requires. Everything will scale up perfectly without blurring or leaving artefacts. So no need to struggle with a too high resolution and slow feedback.