The following has helped speed up my computer. I am using Windows 7.
In most cases a large HOSTS file (over 135 kb) tends to slow down the machine.
To resolve this issue (manually) open the “Services Editor”
Start | Run (type) “services.msc” (no quotes)
Disable all non-Microsoft unnecessary services.
Scroll down to “DNS Client”, Right-click and select:
Properties - click Stop
Click the drop-down arrow for “Startup type”
Select: Manual, click Apply/Ok and restart.
Please see #695 just above