Network Speed Slow and CPU Slow

Overview Copying to or from Apollo was extremely slow....about 100kb/s or less...not even in the MB range.  In addition when copying to or from Apollo the CPU would grind!  Looking at the task manager a "system" task would pop up and be taking 30% or more of the resources to the point of music playing would breakup and you could hardly do anything on the PC....REAL REAL SLOOOOOWWWW!


Did notice that Apollo and Thor are using the Home network and Space and Xavier are using the Work network settings.  This should not make a difference....I think.  All firewalls have been disabled.  Before and after network upgrade did not make any difference.  Upgrades included cabling to Cat6A and a "new" managed switch to replace the Netgear unmanaged 8 port one.  Everything is gigabyte....NIC's, switch, cable (10GB actually).  Realtek TL8111E driver looked up-to-date (actually the driver on the ASUS website was older than the one on Apollo).

Solution: Disabling “Large Send Offload (LSO)”

Large Send Offload is a technique of improving network performance while at the same time reducing CPU overhead. Apparently it does not work very well, so it was suggested to disable it. If you would like to know about LSO, check thisMSDN article from 2001.

LSO is an option located in a Device Manager under your network adapter, so this solution requires Administrator Privileges.

Follow these steps:

  1. Open Start Menu, right-click on Computer and select Properties
  2. Under Control Panel Home located on the left side of the window click onDevice Manager
  3. You will get a list of all devices on your machine. Expand Network Adapters.
  4. Find your Network Card and double-click on it.
  5. Select Advanced tab. You will get a list filled with different options.
  6. Select Large Send Offload V2 (IPv4) and set the value to Disabled
  7. Do the same for Large Send Offload V2 (IPv6) if it is available
  8. Click OK

After clicking OK, I tried to send a file over the LAN network. The transfer speed started very slow, but it was gradually picking up speed. I decided to restart the computer and try to send that file again and this time it worked like a charm.

Now that sending of files worked as it should, I also checked speed for receiving files. It turned out that it was still slow but all I had to do to fix that was to disable Large Send Offload V2 on the other computer. Once done,  the problem was solved for receiving files as well.