When using the razer viper 8khz mouse, the game valorant fps drops.

Polling the USB Bus for mouse information up to 8000 times a second does put a load on the system, especially as this implies techniques that overcome the normal limitations of USB. This amount of polling probably is not necessary anyway, it’s just like having a 12000dpi sensor on your mouse but next to everyone runs their mouse below a 4000dpi setting. Or having a 200 Megapixel camera in a phone with tiny plastic lenses for an optic.

Try limiting the poll rate to 1000, 500 or even only 125 polls per second. This can be done in Razer software on Windows or equivalent on Linux.