Slow file retrieval from archive

Dear EV experts!

Our customer has a test env with EV 12 and FSA archiving.

We have that problem:
- If we click a file which is archived and if we click a placeholder
or shortcut file the retrieval from the archive is very-very slow.
For a 4 Gb file it takes from approx 20 minutes.
If we copy one file from archive share to the Prod share it takes
1-2 minutes maximum.

Question:
---------
1. How can we tune this retrieval speed, which setting should we check on EV side?
2. How can we fix this issue?

BR:
Pal