Neither of mine have ever taken 3 days to recover from anesthesia- they were usually over the side effects by the next morning.
However, some surgeries are harder to recover from then others. When my Chloe had her liver biopsy she took about a week to perk up again.
Also the cones really seem to bother them- so the lack of activity may just be from that. Are you able to give him any supervised breaks from the cone?
Hopefully your baby perks up soon
