How to troubleshoot mongo sharded environment like query slow

i shard mongodb to 3 shards 3 replica and 3 config server 2 router server …
but insert query for a simple user collection is 30 case per 10 sec
before sharding i have very speed 1000 insert per sec
waht happen for performance how can achive high speed

what is your experience
this is not scaling it is like fu…ing scaling