I was copying a few very very large files to my computer. In total, 28 files and roughly 200GB (meaning each one was . I noticed that it was going at more or less the same speeds the entire time:
However, transferring multiple small files has much larger fluctuations in speeds:
(Yes, this is from google drive but they're all locally downloaded to my computer)
To reduce disk fragmentation, the files will will be written to wherever free space is still available on the hard drive.
For instance, there might be a 10 MB contiguous free space somewhere between two large, sequentially stored files.
The 10 megabytes of space isn't enough to store a large 5 gigabyte movie, but it can accommodate hundreds of small, 1-100 KB files (text files, INI configuration files, documents, GIFs, etc.)
When that block is filled up, the HDD will look for other small blocks of free space that it can use to fill with data, which causes the head to move around a lot.
That, along with the overhead mentioned in these linked articles causes small files to take a long time to copy.
