It is a "given" that to run Agisoft Photoscan you need a computer with a fair bit of computing power. I have found it difficult to discover exactly what is required as most online articles seem to lack depth and real world experience with the program. I have found some information on the Puget System website which may be of interest as they seem to be based on actual testing.
Hopefully there will be an update based on the new generation of GPU cards released in June 2016.
This is a commercial site and they are trying to help you purchase computers for them. I have no affiliation with them.