That speedrun logic seems really shaky. Waiting for monsters on the edge of LoS to approach you isn't a major source of turns spent at all.
Isn't that the same with all other melee characters?
Unless I'm playing the game fundamentally wrong, which I doubt since I've won several times.
On the same note if the monster isn't a terrible threat, you actually save turns by walking towards it with Chei. If the monster is melee, it will walk towards you several times in a single turn.
You seem to have dramatically misunderstood what I was saying, so I'll try restating it. The number of turns you spend waiting for monsters to walk towards you is not remotely significant with any character, Chei or not (as you seem to agree?), so the fact that Chei slightly mitigates that tiny source of turn usage is not a great help when going for speedruns. The fact that he makes the game a lot more difficult, thus requiring you to play more cautiously and spend more time resting, accounts for way more wasted turns than the 200 or so turns you might save over the course of the game by allowing monsters to move towards you in fewer turns.
I checked the online stats and I found a really phenomenal
sub-20k turns Cheibriados run from the same player who got a sub-10k win with Ely, but that seems like something of an anomaly considering the second best time with him is over 25k. If you're curious the ranking goes Ely, Trog, Jiyva, Dith, Makhleb, Ash, Okawaru, Zin, Chei if you look at fastest times only (which would put him mid-table).
If you're talking about fast 15 rune games rather than speedruns then I dunno, maybe Slouch combined with the fact that trolls are gigantic sacks of HP would be enough to let you smash your way through extended.