Unfortunately for me, nvidia 555 brought with it some really nasty firefox crashes (default hw acceleration) and system wake (from suspend) crashes as well. Par for the course I guess.
$ journalctl -b-1 -kp3
kernel: BUG: unable to handle page fault for address: ffffbd8024fdac34
kernel: #PF: supervisor read access in kernel mode
kernel: #PF: error_code(0x0000) - not-present page
kernel: BUG: kernel NULL pointer dereference, address: 000000000000032c
kernel: #PF: supervisor read access in kernel mode
kernel: #PF: error_code(0x0000) - not-present page
kernel: Fixing recursive fault but reboot is needed!
kernel: BUG: scheduling while atomic: irq/95-nvidia/49726/0x00000000