General advice:
- where possible avoid all combat and ignore the side challenges and elemental zones
- collect any clocks that are in your direct path, or that are dropped by enemies
- knowing the fastest way through the level will always help
- set the difficulty to EASY
Certain characters will give you a boost too if you own them.
Magna Charge is one of the fastest and his wheel can be upgraded to boost it further and make combat quicker at the same time.
Night Shift's portal ability means he can traverse extremely quickly. He's also one of the strongest characters in the game in combat making him a sound choice.
If you are using Spyro's Adventures or Giants characters, then Drobot's afterburners and quadruple lasers will help a lot.
If you are just playing with the "Starter Pack" characters, then use a maxed-up Stealth Elf and pop a speed boost hat on for good measure.