If I field first, I can tell after 2 balls whether it's going to be a good game. Most good players play normal shots the first few overs unless you bowl with something other than a fast/fast medium, so if they come out and slog they're usually either really bad (90%), which means they will probably quit when they get out for 30, or really good. And if I bowl somebody the first ball there's probably huge lag which also means they will usually quit (which is no prob) since nobody is that bad really.
If I bat first I will usually play out my innings even if there's lag unless it's just ridiculously awful, since I know they will lag too. If I get out for a low total there's a better chance that they won't quit during the chase which means I at least get a full game in. I just pretend the lag is like "tough batting conditions" which is actually pretty reasonable, given that the in-game conditions have no effect on batting really.