When I use the belt sander on PVC deck boards is when I get melting, if I try to take too much off at once with a fine belt. I don't seem to have that problem with 60 grit.
I sometimes get wispy trailers, like spider webs, if I try to rip it on the table saw with a duller blade.
Heat buildup seems to be the common denominator, so keeping my tools sharp, whether it's hand tools or power tools, has been key for me when I'm working with PVC, especially the deck boards.