Hello Dheeraj
You probably need to configure the settings in Navigation/Native Mobile/Configure Sync to constrain the amount of entities been sync’ed.
In addition, there's an excellent demo project that uses incremental sync to mitigate this kind of problem. Please see the link below:
https://marketplace.mendix.com/link/component/118076
Finally, be aware that if you proceed with the logout after using your app, the local database is swiped out. So, in a subsequent login, a full sync will be performed, potentially causing a delay depending on the amout of objects to be sync’ed.