Hi kalairasan ,

Some of the point i would suggest is ,

1.If you’re using many microflows , in the piece of code is reuse try to reuse it.
2.If you're processing huge number of the records try to process it in batches
3.Try to avoid calc attribute entity in the microflows
4.In the page if your first time loading the data use the microflow , from the page 
you're doing some process with records try using the nanoflow which will run in client side only
5.Try the avoid the committing of objects inside the loop
6.Wherever you can change microflow to nanoflow try to change it
7.Prevent unnecessary retrieves if objects or lists can be passed as parameters
8.Add indexes to the attribute mostly used for retrieval

Below links for your reference 

1. https://www.mendix.com/blog/3-ways-improve-performance-mendix-apps/
2. https://docs.mendix.com/howto/monitoring-troubleshooting/detect-and-resolve-performance-issues
3. https://docs.mendix.com/howto/general/community-best-practices-for-app-performance
4. https://docs.mendix.com/refguide/performance-best-practices

If you have a licence for ACR you can check your code and see where you violated the best practices. Also you could use APD on your environment to see which microflow actions are slow.