The flashfire build is alot slower. The Db gain / time spent is alot better with my archon variation.
You're playing it wrong then. You need to have In-Geom cubed - You kill an elite/champion - you gain the In-Geom proc - teleport to the next elite/champion and kill him. Don't need to kill everyone, just enough to proc In-Geom. You can do a Tier 13 in less than 3 minutes.
WIth the FlashFire build I've often tried both Aether Walk and In-geom. But, I feel like even with either of those, the build is still very slow.
Removing any peices from VyrRasha L-Archon will make it really weak. For your current build, I'd swap Ray of Frost with Arcane Torrent - Static Discharge and remove Lightning Hydra in favor of Blizzard - Snowbound. You could also use Frost Nova - Frozen Mist in place of Blizzard. I like this build for farming because its very fast, you don't waste time placing Hydras. I farm T13 with this in about 7-10 minutes, it's very efficient. I've also started to use this set in Grifts when I want to level gems for augmenting.