Welcome to Windows Central.
It would be beneficial if we would know what phone you're using and what OS version it is running.
If you're referring to a Windows Phone, then there is no such app that would increase the performance of your phone. The best things that you can do are:
1. Uninstall any third party app that you are no longer actively using;
2. Disable apps that are unnecessarily allowed to run in the background (in Battery Saver);
3. Restart or perform a soft reset on your phone;
4. Perform a hard reset on your phone.