According to Massachusetts Society for the Prevention of Cruelty to Animals-Angell Animal Medical Center (MSPCA-Angell)[1]https://www.mspca.org/pet_resources/ask-a-vet-all-you-need-to-know-about-spayneuter-surgery/, a male cat neuter can be done in under 2 minutes.
(A female cat spay is generally fifteen to twenty minutes, depending on her age and where she is in her heat cycle. Female animals in heat can take a longer time because their reproductive tracts are much more fragile and hold more blood when they are in heat).
Most cats recover very quickly from the surgery. Usually, within 10 to 20 minutes they are awake enough to walk around. According to be.chewy [2]https://be.chewy.com/cat-neuter-surgery-from-start-to-finish/, most cats can resume normal activity 3-5 days after their surgery. It is imperative to control your cat’s activity after surgery, as excessive activity can cause swelling and open up the incision. Make sure to follow all post-surgical instructions from your veterinarian exactly.