Profiles are data-objects containing all information about a user (such as trades, transactions, personal details, phone numbers, linked bank accounts, etc.).
Depending on the past activity of a user, this request can be relatively sizable and take a while to return the data object.
Please consider using the Basic User Profile Endpoint to fetch a reduced data object on the user where possible.
Note: Wallet balances, transactions, deposit keys, and more can be pulled via the Wallet Functions Endpoints.
