How do I interpret gc messages?

I set gc-hook to t to see what would happen. What do these messages mean? Examples:

[ gc: total 82640, [ny:gc-hook allocating 2000 more cells] 28173 free; samples 953KB, 0KB free ]
[ gc: total 84640, 28202 free; samples 953KB, 0KB free ]

I was trying to use some tricks in my code to reduce the amount of consing to make things a little faster, with no apparent benefit.

I’ve not got much information on that, but there is some information in the XLISP manual. If you’ve not already done so, have a look at these (and associated) pages: