Through years of shooting airshows as photographer I've seen more than a few WW2 vintage airplanes pull enough G to generate wingtip vortices. Watch Dale "Snort" Snodgrass perform a demo in the Kalamzoo Air Zoo's FG-1D and you are likely to see it.
The weather conditions need to be fairly specific for them to occur, though - High relative humidity with a very close dewpoint/temperature spread. They are very likely to occur near and at the same alitude as visible cloud formations or overcast.
Sounds like two different things are being discussed in this thread.
Contrails from engines are quite different in cause, occuring well below the dewpoint as a result of water freezing in the exhaust exhaust stream. They are really trails of frozen water vapor (ice) whereas the wintip vortices are momentarily trails of water vapor that has condensed enough to become visible.
Performance wise, I think my computer (P2-400) could take the small frame rate hit of momentary wingtip vortices but masses of dynamic contrails at high altitude would severely erode fps (I get 4 fps avg around airfields with 2-3 columns of smoke). While either would be great eye candy, I'm not sure that I would want any frame rate hits when fighting against another airplane, much less a bunch of aircraft, pulling vapor. A toggle on-off for such effects, if ever implemented, would be needed for those flying on low-end systems.
MiG
