Constructive & Helpful!
HE's DPS is absolutely *abyssmal* compared to CA, which just makes the fight last even longer and give the enemy even more chances to hit you and end your life, I cannot stress enough how CA actually having very good DPS for how powerful the class' dodge aspect is helps to consistently pull off the solo, since less turns means less dice rolls.
If you can keep up Enrage for most of the fight, it's actually not that bad, and that is entirely possible, more so with Mana Vamp. Essentially, the DPS of Horc is dependent on your ability to save up mana for Enrage. It may be worse than CA still, even if you kept it up 100% of the time, which I am sure is possible, somehow, but I will take what I can get as a non mem, it gets the job done all the same.
At lvl 90 with 2 Thief enhancements (and probably around lvl 70 or so with full Thief), you can get enough dodge to never get hit and consistently keep all that dodge by looping your skill buffs, so the only time it ever matters how long it takes is if:
1. You are in a hurry for some reason.
2. You get lazy and let your dodge buffs fade.
I have found a pretty surefire way, although not the best in terms of damage to keep up my dodge and haste and still be able to use Enrage every so often. Once fully stacked, every time I use Shadow Strike once, I use both Smell fear and Hunter's call, after which I wait 5-6 auto attacks to use Shadow Strike again. It doesn't leave a lot of mana left unless you get some Mana Vamp procs, but it's a lot less stressful than manually trying to manage all 3 buffs at once. If I was going for damage, I would definitely mix it up a little to try and save mana, because with this rotation, you do still have a bit of time left that you could make better with on Hunter's Call and Smell fear.