Despite a lot of jokes and offended Yelp reviews I see accusing virtually every restaurant at every price level of that, I'd be surprised if any were literally microwaving frozen meals to serve. They use a lot of frozen and canned ingredients for dishes, and probably use mixes made for them in commercial kitchens and shipped to the restaurants. But a little cooking at the end can go a long way.

Chili's, for instance, serves not only freshly made salsa but freshly fried chips. The tortillas are pre-made and pre-cut and just need to be dumped in the oil, and you can make salsa in batches by dumping pre-measured portions in a blender. Panda Express is cooking everything on site throughout the day, too. Take the right bags of pre-cut vegetable blends, the meat, the sauce, stir it all furiously in a big wok, put it on a heat table. No microwave.

Most of the speed of "casual" restaurants just comes from doing a lot of prep work ahead of time, keeping everything from sauces to precooked vegetable mixes in warmers, and using the same ingredients across a range of dishes. (Prepare five grilled meats, six sauces, and put them on beds of rice, mashed potatoes, or pasta, and now come up with a name for each possible combination. Presto! You're a Cheesecake Factory.)