Another thing you can do is to place jugs of water in the fridge and the
freezer if you have space. This displaces the cold air that falls out
every
time you open the door so the compressor doesn't have to work so hard.

I doubt that if your "did the math" you would find it hard to justify the
water jugs on the basis of energy conservation.

One "fill" of air doen't actually represent much heat energy (or lack there
of).

But when you do open the door, the cold air is almost immediately replaced
by warm room air. That warm air starts to heat everything in the
compartment: both your stored food AND your water jugs. The most "stuff"
you have in the ice box, the most heat is transferred from the air to the
"stuff."

Moreover, the more 'stuff' (including water jugs) you have, the longer it
will take to store or retrieve the food and, thus, the more time it will
take the compressor to restore the proper temperature.

If you live in a area where the power goes off often, it's often a good idea
to keep some water jugs in the freezer. The drill starts when the fresh
food compartment temp gets above 40F or so. That's when you take your
frozen water jugs from the freezer and put them in the fresh food
compartment. By that time, your freezer compartment is around freezing
and, in fact, your frozen food should either be consumed or disposed of.
Most frozen foods should be kept below 20F. At even 30F, because of
dissolved solids, the food is starting to thaw.