[Boost-users] map with minimal memory footprint

Hi all, I'm using a rather big std::map which gives good performance but the memory footprint is a bit too big. So I figured to implement an std::map as an std::vector<std::pair<T1,T2>> but thus with the interface of an std::map on top of it. I kind of recall a similar discussion and checked in the boost-sandbox but did not find anything similar. Anybody knows of implementations like these? Thanks, toon