fastest times
Have you ever timed yourself playing portals? It can be kind of fun.
I measure from the time the first portal opens to the time I destroy the last aperture science thingy. With loading times I managed 46 minutes. what are your records?
46 minutes is a load of crap.
But no i havn't played the missions all the way through since i finished them the first time.
I wouldn't say it's a load of crap, I finished it before 1:30am on the night of release, even after I was stuck at that god-damned vent with the rocket turret for like 20 minutes.
next time i'll make a video.
think about it though, if you can do the individual challenges all under a minute (which has been done) then it's possible to cut the total game time down by alot. but i'm not lying.
haha, after watching those speedmaps that people do, i believe anything.
Good God, the stuff that people manage to do.
I stumbled upon that answer out of my first curiosity of the area. "I have a destructive device at my disposal. What can I destroy?"
46minutes isn't completely insane, i did it in 57 minutes in order to get
my camera shy achievement. I only know this b/c I was trying to get it
done before my g/f came home and I started a seven, and watched the
credits, which took till about 8:02 or so... I took the shortcuts for
a lot of the levels (ie the fastest times from 13-18 challenges. Those
tricks I learned helped a lot, that and knowing the level ahead of time.
that's even with quicksaves on attempts of difficult maneuvers and quick
loading back into the same room to try again.
Hell, at the end,
landing on the platform and just shot a portal high, jumped through the wall
and portaled over to the top level before the lift had gotten halfway into
that room.
My top record on a SS run is 31 minutes, however it is done with 0 use of wallclimbing (I do use 2 cameras to boost the cube on chamber 17 though), but some portal in portal is used.
18m05s is very good, and I would have to segment a run greatly to achieve this score. I think with a bit of practice I could bump it close to 20 minutes, but sub 20, I don't think so.
I didn't really time it but I think I got 45 minutes?
Yeah, in addition to this, there's already a speedrun, single segment running
around as part of two 9 min videos. So, now I'm defintely convinced that
46min is possible 
I knew it was unlikely, but I never would've expected
some of the shortcuts I saw in that vid.
This goes to show you, even the EXPERIENCED mappers can't plan for
everything to go their way, just try to figure out whether it's something
that's a viable option.
Someone's going to find a shorter way through your map, no matter
how many precautions you take, so just do your best to make it decent
and let the speedrunners play with it ^^