My 2 cents. The cold can affect efficiency, especially in spool valves. There could be a few things working against you though.
One, what was the gun chrono'd at? Could have been high and maybe you didn't notice just by shooting.
Two, how good was the paint to barrel bore match? If you over bored, more air escaped for each shot.
Three, when you say hopper and a half, what size hopper (how many balls)? Some hoppers are bigger than others (a Prophecy can hold more than a standard Rotor).
Four, if you truly are having issues with the TechT bolt, that could contribute to poorer efficiency.
Lastly, 2000 PSI is usually the warning mark for me that I only have a few pods left anyway. I will get a fresh fill before playing the next game just to be sure. Hope this helps.