Microwave cooking time with porcelain/stoneware container rather than plastic Would the cooking time change if I microwave some food in a porcelain or stoneware container rather than plastic?

More details (if you have time to waste)

I generally do not like to put plastic in the microwave. I had some accidents in the past where the plastic softened or even melted. In those cases I had to throw the food away because honestly the idea of accidentally ingesting plastic scares me. And this happened even when plastic containers were claimed to be microwave safe.

Therefore, recently I decided to move food from plastic "microwaveable" packages to my own microwaveable porcelain and stoneware containers (dishes or mugs with lids).

Would this mean that I have to cook the food for longer time or shorter time, compared to the cooking time suggested on the package?
Yes, it's likely to change the time. There is no way to predict how it will change it, though, since it is a combination of the material, mass and shape of the vessel. So you'll have to test it for each vessel you use.