Apple designed your iOS device’s Lock screen to go back to sleep after a predefined timeout period, and while this can be useful for battery savings in certain circumstances, there are some instances where this might be irrelevant or where you may favor performance over battery life.
For that reason, iOS developer Nepeta came out with a new free jailbreak tweak called NoIdleTimer that lets you disable the Lock screen’s automatic lockout period so long as certain conditions are met.