Clicking "Import Contacts" button in the Contact Management module is too much slow.

Clicking @Import Contacts@ button in the Contact Management module is too much slow, taking approx 30 Second to load.In the Contact Module in the @OM_Contact@ table, we have 155055 records, size of the @OM_Contact@ table is 284MB.Our sites are deployed in the Azure and Pricing Tier is Premium P2V3, So we are using enough resource and already did the DB Indexing but the issue didn't resolve. Please suggest how to resolve the issue.