Hello mmlab,

It's great to see COCO and LVIS API merged into one repo.

However, the original python api still suffers from slow evaluation speed (~ minutes). AFAIK, NVIDIA has brought a C++ extension (https://github.com/NVIDIA/cocoapi/blob/nvidia/master/PythonAPI/pycocotools/ext.cpp) , which can print the mAP & mAR table in less than one second, nearly in a flash. Would you consider introducing the extension into this repo?