I just found that in Dosbox (don't know from which version on) there is a magic button (or combination of buttons) for fast forward (aka unlimited speed, aka speed disaster, etc.). Which is great when you want to skip fast some parts of a game or demo or for any other reason. It actually works very nicely, depending on the machine cycles you have set, things might go quite fast and even the music is funny.
My dilemma is that it enforces some bad habit I have with demo watching and never told you. When I am in hurry yet I want to see some old demos I didn't knew before, searching maybe for an effect or a screen that could impress me, instead of watching the demo as a regular scener watches them, I press the fast forward after I have seen each effect. Ok a logo, fast forward, stop there, nice blobs, ok I saw them, fast forward, wow great voxel! Fast forward, etc, etc.
I used to do this with emulators in AtariST demos, Spectrum, AtariXL, C64 and everything that has an emulator enabling fast forward. I am wondering now if WinUAE for Amiga does have one and I don't know it. Or about CPC? (Winape32 has the option but you have to do it from settings. I want a button that goes fast forward while you pressed it and then you can release it and everything goes to normal). Oh no!
At least when I want to watch again some old classic demos I don't do this. There are two kinds of demowatching, the one where you want to enjoy the demo as a demo and the one you are in a hurry to pass through it's parts in the hope you will enjoy a good effect. Also if in the middle of this heresy I discover that the demo I fast forward is actually worth it for it's flow and transitions and presentation then I do the exception to quit and lay back and watch it from the beginning in it's normal pace.
Imagine what would happen if I watched demos with friends and I suddenly touched that keyboard :). I did it in other ways though, like pressing and un-pressing manically the turbo button on my 386 at each part while my brother was watching, and I was talking to myself: Wow, the gouraud shader runs smooth even without the turbo button. Wow! Like who cares? Hahaha!!!
I am just insane about coder effects and performance. I do it in dosbox by changing the cycles up and down while watching a particular demo :)
p.s. Actually dosbox has become really good. There is even a mode (if you set machine to vgaonly) that tries to emulate the VGA properly with it's right timings so that games and especially demos that might use hardware tricks to do raster effects and splits and cooper bars and all that stuff work. I tried it with my 256b intro kefrens256, a quickbasic secret part for Deedline Sax where I was displaying similar stuff, my CPU meter in demos, then tried it also on some PC demos using tricks (DoWhackAdo, David CopperField work great, but Copper by S!P doesn't work very well). Also you can choose the CPU strictly, for example a 386 only CPU to not have to emulate 486 or Pentium if you don't need to, etc. And that's not the only cool think about new things dosbox brings. I am curious to see what the next versions might bring.