At times I have to connect to work through a VPN, and sometimes the connection is slow. However, I've noticed that when the network is slow, EVERYTHING on the computer is slow. For example, navigating around my local C: drive is slow, even though nothing should be going across the network. It can take up to 10 seconds for the context menu to come up if I right-click on a folder. It takes another 5 seconds to navigate to a subfolder. When I disconnect from the network, I can still access everything on my local machine, and everything is MUCH faster.
Does anybody know why this happens, and is there a way to fix it?
Something to try: Go to Folder Options, the View tab and uncheck "Automatically search for network folders and printers" and see if that helps?
As Alexander Taran points out in his comment, this is often due to shell extensions that try and do something on the network.
If you have drive connections to dead network shares then that could contribute to your problem also. You'll notice this slowness a lot when clicking on the Address drop-down in Explorer to change drives or the Open In / Save In dialog when opening and saving files.
Don't use mapped folders. Portions of the OS treat them as if they were local. If you need to access network folders you can use "My Network Places" on XP or similar on Vista. Using the full UNC (\machine\share...) instead of mapping a drive letter can really help.
I've been doing this for years and get much better performance. It also helps me to remember where the files really are. This is useful when I go to another machine that does not have the same drive mappings.
FWIW, I've found my computer having lots of issues if I don't set the VPN connection to not use the VPN as the gateway when I'm connected. It's set by default and directs all network traffic over the VPN, not just traffic destined for that subnet. It prevents one from browsing the web while connected to the VPN, as one side effect, and I've noticed it causing my computer to crawl in explorer as well.
If you're using windows, you can change this easily go to the TCP/IP settings on the VPN connection's network tab, open the proerties, and hit the advanced button. Un-check the use default gateway button.
for my windows 10, Go to Folder Options, the View tab, Advanced settings, uncheck "show sync provider notifications", uncheck the "show preview handlers in preview pane" helped the file explorer and context menu loading.