Windows 8 and above adds a significant delay before launching applications at system startup.
The Remove Startup Delay button lets you remove this delay. Changing this option affects all programs launched via the Start Menu startup folder, not just Opus, and the setting is in the registry rather than the Directory Opus configuration (so you'll need to change it on individual machines if desired).
This is a Windows setting, not an Opus one - we just provide a convenient way to change it in Preferences. You can use the Restore Startup Delay button to turn it back on again if you've previously removed it.