I'm not a game developer, but I was similarly lead to believe that stl containers were especially slow compared to other implementations. This is supposed to be because the stl has more restrictions on the implementation owing to the interface they have to export. The stl hash table for example has to provide low level access to the buckets, even though modern hash tables usually avoid having buckets in the first place. By lifting these restrictions the performance can be improved tremendously. Facebook, for example, are supposed to have their own in house hash table implementation to achieve this.