I try to implement c++ code that get about 800.000 document in a collection has 30 field (types include int, double, string), It take more than 240 seconds.

To count duration time, I seperate code into 2 sections. The first invokes DBClientConnection::query to get all from collection and return vector of BSONObjs, it take 20 seconds. The last iterate that vector and parses each of BSONObj to a C++ object, using BSONObj::getField().Int() (or Double(), or String()). And, more than 200 seconds!

Please consider and give me some advices to improve it.
Thanks you.