Outside of slow cooker seems to be losing heat

Addiscomber

Shamed by the enthusiasm here for slow cookers, I have dug my almost 30 year old model from the back of the cupboard and started using it. It seems to me that an awful lot of heat is being lost to the outside, and I wondered how hot the outside of current models gets, or whether they are better insulated?

I don't suppose there would be enough difference to justify buying a new one, though. I wondered whether making a quilted jacket to go round the outside (not over the top) would be safe? Or even make any difference to running costs?