[placesalt]

The effect of caching on Windows can be quite pronounced if you process large datasets on a machine with a large amount of RAM.

If, say, you have 256GB RAM and a 100GB folder of ~1GB files, you will only ever have a few GB used actively. A first pass of processing over the folder will take a long time (reading from disk). Subsequent passes will be much faster, though, because reading is done from the RAM-cached versions of the files (the output from the previous run, was my understanding).