Depending on what your preferences are, custom super-hard "parkour" race maps in GTA Online are either the game's saving grace or damning bane. These races fill up the list of community maps made with the Content Creator. Everyone who falls outside the very small niche that enjoys them finds it a chore to sort through it all. At the same time the core stunting and "parkour" community within GTA V's player-base spend most of their playtime on these maps and rarely venture into other game-modes.
These maps are built to be extremely difficult to traverse, forcing racers to brave massive jumps, long wall-rides, loops, jumping puzzles, traps and much more. Successfully completing such a parkour map requires perfect timing, an intricate familiarity with the map and your vehicle of choosing, lots of patience, skill and significant know-how as to how GTA's special brand of physics works.
Due to their difficulty many of these maps take quite a bit of time to master, however once you know how to get it done, they can be completed in a relatively short amount of time. This has led rise to the speed-running community within the aficionados of these GTA Online parkour maps.