How to speed up an import

I am trying to create a secondary photos library for my family photos, it all went according to plan, wiht 7000 photos imported and then I came to a folder with 12000 images, not in folders just scattered loose, (yes, my family is terrible at managing photos, then again, they were trying to do it on a Windows 7 PC with no photo managing software)... I selected it and started the import and then left it running overnight and it has only finished importing about 20% of them.

Is there any way to speed up the process? I had a look in the finder and that folder I am importing from is taking up 120GB of space.

I checked activity monitor and the computer isn't being overloaded in the processor, RAM or hard drive.

It is a late 2014 Mac mini, with I mainly use as my photography workstation. It has a 2.6 i5, a 1TB standard hard drive and 8GB RAM.

As a side issue, would a Mac with 4GB of RAM be able to comfortably manage a photos library with 20000 images? I am the only one inn my family with a decent computer at the moment, as the family PCs hard drive is on the way out, and everyone else either have iPads or netbooks. I am thinking about getting an entry level mac mini to replace it, would that handle the full library?