Sure, I read it more the other way around, the bloom filter thing is part of an ongoing thrust (like horton) to reduce the number of memory accesses for bucketi

Sure, I read it more the other way around, the bloom filter thing is part of an ongoing thrust (like horton) to reduce the number of memory accesses for bucketized cuckoo (2 on failure, 1.5 on success) down closer to 1. But in the case of flow-tracking, many more memory accesses would be needed to organise a heap or timer wheel, so that's where the main win is, compared to an incremental improvement on bucketized cuckoo / horton.