Is this taking into account any of the memory savings that would be seen from common paths using the same memory? If a lot of entries have similar prefixes, this can lead to a lot of deduplication.
Depends on the randomness of the paths. With URLs coming from a limited set of websites - yes, there would be some savings.
With a set of random strings, for alphabet with 64 chars, there are 16M different 4 character prefixes, so the savings from overlapping prefixes for 128char long strings is likely less than 3%.
With a set of random strings, for alphabet with 64 chars, there are 16M different 4 character prefixes, so the savings from overlapping prefixes for 128char long strings is likely less than 3%.