Checking for a contact in a contact application (Swift)

Question

Now I am creating an application that provides contact synchronization. To do this, every time the application returns to the forefront, I check all contacts (CNContact) and compare it with my contact in the main data of the application and find out if any contact is different and combines the data. It works fine, but it takes up a lot of memory.

Is this any way to determine if a contact has changed in a contact application without comparing all contacts?