Steps to reproduce:
1) Download user's attached project
2) Open downloaded project with Unity 2017.3.0p4 or older
3) Build and run the project on an Android device
-- Notice that Average Delta time is about 16.90ms and Average FPS is about 59.17
4) Close the project and remove Library folder
5) Open the same project with one of the newer Unity versions
6) Build and run it on an Android device
-- Notice that Average Delta time dropped to 20.63 and Average FPS dropped to 47.95

Note:
Stats are getting even worse over time

Reproduced with:
2017.3.1f1, 2018.1.0b9, 2018.2.0a1

Unable to reproduce:
5.6.3p1, 2017.3.0p4

Devices under testing:
Reproduced with:
Xiaomi Mi 5s, Android 6.0
Samsung Galaxy S6 Edge, Android 6.0
Google Pixel 2, Android 8.1

Unable to reproduce on iOS