Actually, on FT the cards are in a constant state of shuffle and are dealt 'on demand'. I have the tech support e-mail from Tilt that confirms this if you'd like to see it. Their 'reasoning' is that no one can ever tell what card is coming next from a 'set deck' and entropy to the RNG can and WILL change whatever the next card. Not to any 'specific' card, just not the card it would have been as events affect the next card/s.
OTOH, Stars does set the entire 52 card deck before the first card is dealt. Nothing changes the order of delivery. This is in their website security section at:
PokerStars Software Security - Secure Online Poker
I haven't researched the smaller sites, so cannot comment on how they perform their shuffle and deal.