SQL restore duration
Some of it will have to do with caching on the remote machine.  You've also got to account for what else is flying across the network.  Also some of those blocks may be in cache on the SQL Server's disk cache (not SQL's buffer pool) as they are the same exact blocks the disk may use the cached copy not the actual page you are restoring.

Don't forget things like witches, gremlins, boogie men, etc.