bttray.exen is the traybar process for Widcomm Inc Bluetooth products. It gives you easy access to the configurations and settings for the Bluetooth products.
It is not an essential process but is obviously required for the correct functioning of the programme in question.
Non-system processes like bttray.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that over time your registry suffers fragmentation and accumulates invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues