Unfortunately std::deque is hobbled in the Microsoft implementation. Its block size is such that if T is larger than 8 bytes it devolves to a linked list. And

Unfortunately std::deque is hobbled in the Microsoft implementation. Its block size is such that if T is larger than 8 bytes it devolves to a linked list. And it can't be fixed due to binary compatibility. https://github.com/microsoft/STL/issues/147 https://github.com/microsoft/STL/issues/147 By contrast the GNU implementation has a block size of 512 bytes Fortunately in high performance systems the times where you actually want an unbounded queue are limited.