File copying speed questions
Speeds can fluctuate for a few reasons. First, the transfer generally start off faster then settle down due to the file transfer using the cache of the drives and the burst speeds of the drives/connections.
Also, speeds can vary during a transfer because writing/reading different size files will affect speed. So if you are reading/writing a bunch of very small files, the transfer speed will generally be a lot lower than if you are reading/writing one large file.