Curious about using styrofoam cups in place of 4" plastic pots.

I have many cuttings that are ready to move up to pots. In the past I've used a combination of plastic 4" pots I've collected until I ran out, then started using the styrofoam cups because they were quickly obtainable and they seemed an ecomical substitute. Now, I'm not so sure about the economical standpoint: seems I have a substantially higher mortality rate with the styrofoam than with the standard 4" pots. Maybe it's something physical such not large enough drainage hole(s), maybe something leaching from the styrofoam the plants don't like. I'm not fully convinced something is leaching, I'm just "thinking out loud". But, I thought I'd ask some opinions before I wasted any more time and plants while trying to figure this out. Plus, I do believe I'm a bit too impatient to take the wait-and-see route and take the chance of loosing more plants while I experiment.