When does this happen? Often when you first boot up your computer, there is an antivirus scan that can slow things down; right click on the taskbar and chose Task Manager". Check under Processes/Apps and Startup Apps that may be running and keep an eye on the drive led, which shows when the drive is working.
You also mentioned the Ethernet, I assume you mean your Internet connection. Is there a reason your Internet speed could be lagging? Is this a recent continuous issue, or is it intermittent? If you share a connection with someone else and they are simultaneously using the connection that can also slows things down. I would certainly look into your Internet speed, if it is an issue, find out if your connection is being throttled, and also determine when you're Windows updates or other files are being are being downloaded.