DataLoad can often send data and keystrokes to target applications far faster than they can be processed. Whether this happens or not is entirely dependent on the 'speed' of the target application, which is in turn dependent on what that application is and what hardware it is running on. Delays are often required at key points in the load to prevent DataLoad from overrunning the application with keystrokes, which would undoubtedly result in errors and unpredictable behaviour.
There are two types of delay:
Cell specified delays using *SLn
Preconfigured DataLoad delays. (The preferred option)