I decided to stop fooling around and dig up my DVD of ST:TWOK. It’s the 2002 “Director’s Edition”, but I don’t expect there will be any relevant variation from the theatrical release.
01:07:02 - Kirk, McCoy, Saavik, Terrel and Checkov are in the Regula One station’s transporter room. Kirk communicates with Spock, asks for a damage report, gets the “by the book” reply. Spock says “restoration [of main power] may be possible in two days”, which Kirk interprets as meaning two hours. Kirk and the others beam down to the center of the Regula asteroid. From here, the action is essentially continuous, right up to “KHAAANN!” at 01:13:40.
Then there’s a break in the action, and at 01:13:51, Saavik is on her communicator, trying to call the Enterprise. Characters that were previously standing are now sitting, and clearly some time has passed. McCoy says “He’s coming around” about Chekov. At 01:14:34, Kirk asks if there is anything to eat. Carol Marcus tells David Marcus to escort McCoy and Saavik to the Genesis Cave, which he does reluctantly. Carol and Kirk have a conversation, partly about David. The action is more-or-less continuous (with a brief cutaway scene of the Reliant getting its impulse power restored and gearing up to finish off Enterprise). Carol Marcus says at 01:18:49, regarding the Genesis Cave: “Can I cook, or can’t I?”
Then there is a break in the action, and Reliant approaches the Regula One station, expecting to find and destroy Enterprise. To their surprise, Enterprise is missing.
Another break, and at 01:19:14, the camera is back at the Genesis Cave. Conversation is continuous until 01:20:07, when Kirk flips out his communicator and says “Kirk to Spock. It’s two hours. Are you ready?”
So, I figure there are a little more than 12 minutes of film time representing two hours of actual time, and only a few places to fill in the gaps.
10 minutes between “Khaaan!” and the beginning of the scene where Kirk asks about food? Sure, why not?
30 minutes for Reliant to circle the asteroid, looking for Enteprise? Sure, why not?
An hour passes while Reliant hovers around the station, pondering it’s next move, while everyone hangs around in the Genesis Cave? Okay.
Well, that’s 12+10+30+60… and we’re still short by eight minutes.
And just for good measure, I’ll watch the “Khaaan!” scene again with Nicholas Meyer’s audio commentary and Michael Okuda’s text commentary. Meyer’s just talking about general movie-making stuff, screenplays and junk (and amusing, he speaks negatively of the whole “director’s cut” concept of restoring scenes that were initially cut for being unnecessary) and Okuda’s text is about the technical aspects of the special effects and whatnot. As the “Khaan!” yell approaches, Meyer is talking about Ricardo Montalban’s dramatically understated and menacing delivery, and is talking about Montalban’s stage career while Shatner yells, with no commentary on Shatner’s performance at all, let alone that he was playing Kirk as “faking”. Okuda gives no indication in that direction, either.
If you want to interpret it that way regardless, more power to you.