MDynamicEQ's latency is nowhere near Ozone's (which necessarily requires large buffering to do what it does), but is slightly higher than a straight equalizer. It's also a little bit more CPU-intensive than FabFilter Pro-Q2, which is extraordinarily light on CPU.
 
As the name implies, it is a dynamic equalizer, not a multi-band compressor. The distinction is actually pretty minor: a dynamic EQ can be more transparent than a multi-band compressor. Pro-MB in its default mode is actually a dynamic equalizer, despite the "MB" in its name and the way it's described by FabFilter. Pro-MB can be either a dynamic EQ or a multi-band compressor. MDynamicEQ is just an EQ, all the time.
 
MDynamicEQ is neither a memory nor a CPU hog. It's reasonably efficient in both metrics considering what it does. It'll only start getting heavy when you use the Spectragram, which is one of its key features. But you only use that when you're initially setting up the EQ, and it's GPU-accelerated, which can greatly reduce the CPU overhead.