You can scale memory use to the GB range while remaining instantly verifiable.
Trading off memory for time is not so feasible, incurring an extra order-of-magnitude slowdown.
interesting, could this be a good deterrent for asic? without the need to upgrade the algo each time?
To the extent that DRAM is an ASIC for reading and writing bits at random
(which is the bottleneck in Cuckoo Cycle) everyone already has an ASIC for this.
Changing PoWs is a not a feature you want in a truly decentralized coin.
Instead Cuckoo Cycle could dynamically change its size as I explain in the whitepaper.