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I have noticed that the std::map implementation of Visual Studio (2010) allocates a new single block of memory for each node in its red-black tree. That is, for each element in the map a single new block of raw memory will be allocated via operator new ... malloc with the default allocation scheme of the std::map of the Visual Studio STL implementation. This appears a bit wasteful to me: Wouldn't it make more sense to allocate the nodes in blocks of "(small) n", just as std::vector implementations over-allocate on growth? So I'd like the following points clarified: Is my assertion about the default allocation scheme actually correct? Do "all" STL implementations of std::map work this way? Is there anything in the std preventing a std::map implementation from putting its nodes into blocks of memory instead of allocation a new block of memory (via its allocator) for each node? (Complexity guarantees, etc.)? Note : This is not about premature optimization. If its about optimization, then its about if an app has problem with (std::)map memory fragmentation, are there alternatives to using a custom allocator that uses a memory pool? This question is not about custom allocators but about how the map implementation uses its allocator. (Or so I hope it is.)

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