in reply to constructing large hashes

I have a simple question, what on earth are you doing that could require a 4 million entry hash? the collisions on that in a 32bit space are not going to be pretty, and the build time will be silly. Unless you're doing a shitload of lookups its not going to be more efficient than calculating the entries on the fly, especially if your system is low on ram.

More details on the actual problem would help :)