There is no word that rhymes with slither and means fast.
The closest word is hither, which means come here.
The rest are not related to movement directly at all.
quick
jaguar
flyer
closit
swift
jet
glide
SWIFTj with a soft j
Wriggle or crawl
Well I am from France and the French word that rhymes with loin is Gyhoin it means the rain. American words are coin, growin (if you say it fast), and sewing (say it fast too)
cast
they can slither up to 50 miles per hour