Power Sneakers
From Sonic Retro
Speed Shoes are power-up items found in monitors in most Sonic games. They cause the player to accelerate much faster than normal. The player's top speed is also increased in some games. When they are collected the music usually speeds up or a new music track plays. Usually the reason for a new track being played rather than the music being sped up is due to the game using waveform audio (such as Sonic CD or the modern games), or the game being on a system (such as the Game Gear) that lacks the power to speed up the music and continue the other game processing tasks.
External Links
The Most Useless Power-ups in Videogames - A 1up feature which mentions the speed shoes.