you can also build a kitgun - rattleguts with gibber for fast-firing, splat for crits. You will need to forma it to get the good mods, and add arcanes like pistoleer and precision but then it will bring down the heads in a couple of seconds. Armour strip is the primary feature you should be looking at though, goes much, much faster without armour on the thing.
Nothing much TBH, its not that hard a mission.
However, some things will speed it up for you:
1. a max-range Loki, as one part of the mission is to escort a drone from <far away> to the site. Loki's swap-places ability is beautifully designed for this very section.
2. a fast-firing gun that has lots of crits. The Lephantis you fight at ther end has damage resistance mods, so something that gets past that helps. I suppose a high-multishot shotgun might be good too, but I think they'll have nerfed that after the Archon experience.
This may not be the biggest 2, as I understand they'll be changing things a little. My advice for the caves part at the start is to drop a waypoint as you enter, which makes exiting easier. Otherwise, its run to cave, get gloop, run to drone, defend, slowly follow drone to site, shoot things.
CephalonCarnage's post in Is there a meta primary for hemocyte if you are MR12? was marked as the answer