It’s an ESP32 that’s been optimized to within an inch of its life… They’re great, dual core, feature rich MCUs that pack a lot of functionality on a small surface area, while being quite frugal. You can get them with up to 8MB (slow) PSRAM and 16MB flash, and they can be had as FCC pre-certified modules which helps as well.
They don’t have the raw processing power of, say, a Teensy 4.1, but with some special attention to their strong and weak points (and are not afraid of assembly) you can get some very decent performance out of them.