When Options | Directory Comparison | Other | Parallel file content comparison is enabled and Options | Directory Comparison | Comparison Precision is set to File content comparison (regardless of whether Fast mode is enabled or disabled), ExamDiff Pro first displays metadata comparison results (using only size and time to determine whether files are identical or different), then begins to perform file content comparison in a background task.
While file content comparison is running in the background, a small progress bar appears in the first pane of the main status bar, and new results are displayed as they are ready. The results are prioritized by files' visibility in the comparison window, enabling you to view already-compared files and use other features of ExamDiff Pro while the full comparison runs in the background, with new results quickly appearing as you scroll to a new area.
ExamDiff Pro spawns multiple threads to perform the background task. For advanced users, the thread priority can be modified in Options | Directory Comparison | Other | Background thread.
You can stop parallel file content comparison while it is in progress simply by pressing the ESC key.