Most reputable private servers consider 0 Delay GRFs a form of cheating. While it is not an executable hack, it modifies the client to bypass intended game mechanics.
Players and developers can create custom GRFs to modify or enhance the game's graphics. This can include creating new sprites, such as 0 Delay Sprites, or altering existing game visuals. The use of custom GRFs, however, requires a certain level of technical knowledge and often involves community-created tools and resources.
files with modified versions that have their animation frames removed or shortened to near-zero. : Skills like Sonic Blow Picky Peck Cart Cannon
Here’s a breakdown of what that typically refers to: