A user device includes a memory and one or more processors. The memory is configured to store one or more user applications installed in the user device. The one or more processors are configured to select one or more operations, which are to be performed in normal launching of a user application but not in background pre-loading of the user application, to pre-load the user application before the user application is accessed by a user, including skipping the one or more selected operations, and to complete the one or more skipped operations in response to the user accessing the user application.