At times, you might try to transfer some large files or a large number of files over a LAN and find that the speed is dropping to an insane level.
First thing to try is to disable the "Remote Differential Compression". This feature is to try to save bandwidth in file transfers at the cost of CPU power.
To disable this:
1) Open Start -> Control Panel
2) Open Programs and Features
3) On the left side select "Turn Windows features on or off"
4) Uncheck "Remote Differential Compression" from the list.
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Another area that might be giving you a problem is the network "auto-tuing". Try to disable it and see if it makes a difference:
1) Start -> All Programs -> Accessories -> Command Prompt
2) Type:
netsh interface tcp set global autotuninglevel=disabled
or possibily:
netsh interface tcp set global autotuninglevel=high
If it does not help and you wish to enable it again use:
netsh interface tcp set global autotuninglevel=normal
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Another thing you might watch out for is antivirus and firewalls. Some have had very slow network bandwidth with certain firewalls for Vista.
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One other issue that might slow you down if you are copying large volume files, is the amount of RAM you have in your system. At times Explorer can eat up a lot of memory copying files which can start pumping data out to your swap file which will slow the process down to a crawl.
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If none of these things work, you might also check out this fix from Microsoft and see if it applies to your situation:
http://support.microsoft.com/default.aspx/kb/931770The fix is suppose to be available at:
http://thehotfixshare.net/download/index.php?dir=Language%20Neutral/Vista/ - Can be a handy site!