[Muhznit]

I prefer near-instant. I prefer the kind of "THIS IS HAPPENING, I WILL REACT TO IT" kind of style, if you know what I mean. In general, it should be fast enough that they will see it, attempt to resist in vain, and resolve themselves to their fate.

IMO, gradual process is actually overrated; some people drag it out to ridiculous extents to the point where time progresses faster for the reader than it does for the character. If you will, allow me a short metaphysical example. Imagine two clocks, both set to 7:00 PM. One is set in the story, the other is set in real life. If by the time the real clock reads 7:05 the clock in the story also reads 7:05 (plus or minus a few seconds due to reading speed), then that is awesome, and makes me feel like part of the story. But if I spend 10 minutes reading a process happening in the span of one minute, something went drastically wrong. Don't describe every one of the quantum anomalies brought on by the Higgs Boson appearing in the girl's tits, just keep things concise to a rational level.