Speed run using a 'Wobble Glide' at 0:13 as described here: https://doomwiki.org/wiki/Glide#Wobble_glide http://doom.wikia.com/wiki/MAP19:_The_Citadel_(Doom_II)#Speedrunning
The main reason for this video is to demonstrate this shortcut, but I imagine another 6 seconds could be trimmed off this run by someone more skilled and practiced than me, and 12 seconds more if I could do the unguided glide for the red key, making the blue key unnecessary. Using the popular UV-Speed route is another 14 seconds shorter.
It took me 4 hours of practice to get this down to 1:08 from 2:11 (on my first try) with half of that time spent on the last 8 seconds. In those 4 hours, I learned that the most dangerous enemies on this run are the spectres, cacodemons, and arachnotrons in that order. The spectres body-blocking me at 1:00 made up at least 50% of my attempts.
Played through DOSBox and purchased through Steam at: http://store.steampowered.com/app/2300/DOOM_II/