Background syntax checking enables the IDE to check the COBOL code in the background, as you type it. Any errors are underlined with wavy red lines. Generally, we recommend that you leave Background Syntax Checking turned on. You might consider turning it off only when editing exceptionally large files.
You can turn this setting off or on the Advanced page in Tools > Options > Text Editor > Micro Focus COBOL. The following IDE features are not available when background syntax checking is disabled: