There is a possibility that SSDs could help. I suspect the problem is that you have a lot of machines attempting to image all at once, and each are trying to get the image on their own. That may be causing the source to have to 'seek' all over the disk/file for each piece as it is requested.
I think the availability of multicast in Provisioning in 9.6 will really help out in your use case.
Thanks for the reply. I believe you are right. The decision I have to make at the moment, since our server in the warehouse is being refreshed, is to spend the extra few thousand dollars on SSD drives for the server OR bank on LD 9.6 provisioning on being the answer. I've asked our server refresh team if I could keep the server there longer and if they could put on some performance monitoring read queue or IO issues so I could make a more informed decision. The hardware needs to be purchased in this budgets cycle, and I am trying to avoid dumping thousands extra on SSD if I wont see any benefit or a significant benefit.
I've seen some of the new multicast stuff, and it looks good, and fits your use case well. However, don't count you eggs before they hatch : ). I'm not sure if you are going to get the bump you would like from the SSDs. Obviously, it would be faster, but maybe not enough to make it worth it, and once you do go with 9.6, those drives could probably go faster than the clients can eat it.
Its hard to say for sure without some tests. One possible thing to look at would be scores from CrystalDeskMark (or some other tool) and look at the random 4k scores, as that might be close to what the work load might look like.