[saagarjha]

These days you also get the benefit that it’s four bytes shorter, since it doesn’t have to store an immediate:

  48 31 c9                xor    rcx,rcx
  48 c7 c1 00 00 00 00    mov    rcx,0x0

(This is even shorter:

  31 c9                   xor    ecx,ecx
)