@Ethon, not using STL is great it means it works only with what it needs!
Nope. Every major C++ compiler has a good STL-implementation today and ships it by default.
Irrlicht reinvents the wheel and consists of many container/algorithm implementations which are less efficient than the STL counterparts, not to mention that the design is not as good and it's pretty annoying to convert std::strings to Irrlicht-Strings all the time.
If I remember correctly the MeshCache still uses an array and a binary search instead of a RB-Tree/Hashtable, right?