To avoid any mistakes or errors, I strongly recommend to use small groups of pictures as face recognition. Secondly, I don't think Lenovo Photo Master is a tool to use for such operations. You need to use something light that can browse through the files easily.
A fast computer is also necessary to process the files fast and the Lenovo Photo Master needs to be closed once in a while to clear the cache and the RAM buffer. Simply restart it from time to time to avoid errors.