IL memory - 16k of on-chip memory (base address 0xE5200000), so it's very fast. AHelper confirmed some time ago that it's available for use in our own programs via a bit of experimentation. It's a rather small amount of memory, but still large enough to hold useful data. You might want to put a performance-critical data structure in this memory, or just copy (decompress?) your graphics data here for slightly faster blitting.
This means that this IL memory could be used in critical memory portions for fast processing.
MERAM - 128k of on-chip memory, so the basic use case is like IL memory (base address 0xE8080000), but probably a little bit slower. More interestingly, it can function as a cache for several of the more specialized peripherals. Of those which can connect to the MERAM, though, only one appears to be of use to us on this hardware:
L2 Cache?