Hya and welcome to PCHF,
A quick and easy Googling led me to this:
Will Desktop Search affect my computer's performance? (back to top)
The MSN Search Deskbar uses some of your computer's processing power to build and maintain the desktop index, so you might see some change in your computer’s response time after you install MSN Search Toolbar. In general, this change quickly passes, and you won’t notice it. If your computer is busy, the Toolbar pauses the indexing process until more computer resources are available. You can also temporarily stop indexing.
If you are using a laptop computer, indexing will not take place while the computer is running on battery power.
How long does it take for Desktop Search to finish indexing my computer? How soon can I start searching? (back to top)
The time required for Desktop Search to create the index depends on how much data you have on your computer. If you have many files on your computer, indexing could take a few hours. You can start searching as soon as you install MSN Search Toolbar, but you may not be able to find or search some files until the first index is complete.
After the index is complete, Desktop Search updates it whenever an item is added or removed.
Note: E-mail messages will be indexed only when Outlook or Outlook Express is running
Should answer your question
