RE: Inpiron 15R 5537 - Bad game performance or unability to Sleep/Hibernate?
Please check the Power mode on this case .
As if it is selected to the normal mode then this issue may occur .
So just change the mode by just going to Power Management and select the mode to High Performance and then change the system settings accordingly .,
Try one more thing , just ran Windows Experience Index once and reboot the machine .,
In order to run it , just right click on Computer and go to properties and click on Windows Experience Index .
Hoping it will fix all your issues .
Reply if faces any other issues .