Android client spends lots of time "scanning"

I would like to be able to access photos I took on my phone from my PC soon after I get to my desk. However it often takes up to hours to sync, with most of the time spent “scanning” according to “Upload Info” in the “settings” of the Android client. I do have lots of tiny files in my WhatsApp Images folder (16,191). Does it do a complete rescan every time I leave and come back? Is there a way to cache results, or scan from newest to oldest so the newest stuff can upload while the rest finishes scanning?