Hi,

Flickering issue may have a few causes. It wpuld be difficult to know exactly what is the problem without testing your scene and having access to your render farm. 
The first thing to try is enabling Remember Root Positions in Hair from Guides and Guides from Mesh/Surface. 

The file size of the alembic file will depend on the complexity of the groom and the animation is very long. You may have to split it into several shots. I guess is just very complex. 

If this is happening with a very simple groom then that is another issue. if that is the case we need a simplified version of the scene for testing.

I searched my inbox for emails from you(the address in your profile) and didn't find any new emails from you. Maybe something failed in the contact form.