Anyone who has bought hot food on a cold day has an opportunity to learn about how some containers do nothing and others do quite a bit. Even thin paper versus heavy brown paper makes a pretty big difference in insulation.

Many bags designed for laptops have open cell foam for shock resistance, and thermally conductive foam is a specialty item. You practically can’t make a laptop sleeve without an R value. So it’ll depend a lot on whether your laptop was room temperature when it went in or is warmer.

If you’re looking for a Christmas idea for yourself, I don’t think you find a better laptop bag than Tom Bihn. They have a laptop sleeve that’s practically an insulated lunch bag: https://www.tombihn.com/products/brain-cell with an air gap at the bottom that prevents damage if you drop your bag. Which I have.

Their stuff is expensive, but they’re bombproof and not Apple-expensive. They’re waterproof, including the zippers, the shoulder straps are butter-smooth, and the factory workers are paid a living wage.