The Quick Start feature saves time on counting lines before starting processing.
When this feature is disabled, the program reads the entire file before starting processing to display the number of lines. If the file is large, it may take a long time depending on the speed of the processor and disk.
If fast startup is enabled, the line count will not occur and the program will start processing. Since the number of lines in the file is unknown, you will not see the progress bar and the time until the end of the file processing.