A Synthetic Full is just a consolidation of the previous Full and Incremental.
Could you please elaborate on what type of restore slowness you are getting and for what IDA?
There are various metric to take into account:
- Read performance of Disk Library
- Network between MediaAgent and Disk Library
- Network between MediaAgent and Destination Client
- Destination Client Volume
If you could elaborate on the above we can see what we can offer.