I just added 377,000 parcel polygons that are available to me via our internal portal: I am sitting in my home office and running arcgis Pro 2.5.1 on my local machine. Full disclosure; prior to the test, I randomly copied a parcel id and pasted it into the locate pane. Counting one-one thousand, two-one thousand, I get to three-one thousand for the search to complete as shown in the gif below. (counting while watching the gif is closer to four-one thousand).
At any rate, can you describe how your data is stored and how you are accessing it? Could there be a network issue? Are you remotely logging into your desktop from home? Etc, etc...
That should just about do it....