Hi @Anil_kumar_Narreddi and welcome to the MongoDB Community forum. 
To help you better, we would need certain information with respect to the above request.
- What do you mean when you refer to improve better? What are the metric that you are trying to improve?
- What is the aggregation query that you are trying to use ?
- What is the collection size for both the above mentioned collections?
- Do you have any index defined in the above collections?
- Can you also share the explain output for the aggregation query you are using?
Answering the above questions would help us identify the gaps and help the community to triage better.
Regards
Aasawari