Troubleshooting Computer Performance Using Task Manager
Windows 8 (and to a lesser extent Windows 7) is superb at troubleshooting performance issues - Task Manager has been revamped to show much more useful information. The processes tab in particular, out of the box, can pinpoint a rogue process hogging resource - CPU, Memory, Disk and Network having their own column with an overall percentage of resource used.
Anything hitting CPU and Disk in particular is very easy to spot.
What if you're running older systems still though? It's not common knowledge, but with a little bit of tweaking, you can still access similar information in Task Manager on Windows XP, Windows Server 2003 and Server 2008 too.
The trick is to add columns to the Processes tab. From the View menu, choose Select Columns:
Now, from the Select Columns dialog box, select IO Read Bytes, IO Write Bytes and IO Other Bytes:
When you return to Task Manager, Processes tab, you'll see the extra columns are shown. You can click on the column headings to sort by any column and now you have a much fuller picture of what processes are using the most resource.
In the example below, the SQL Server process is writing most to the disk. In this instance, if this server were running slow, then SQL Server could be the most likely cause.