currently my list has threshold value of 5000, I want to increase threashold and disable trottling. I can increase list threshold value from central admin but that would decrease performance of application. Can anyone provide me powershell script to increase threashold for a particular list only.
You can disable list throttling at specific list SharePoint 2010 using SharePoint Manager or PowerShell script, but you can't increase the threshold for specific list.
$web = Get-SPWeb http://myserver
$list = $web.Lists["MyCustomList"]
$list.EnableThrottling = $false
Remember: Disabling it will cause performance problems as suggested by links provided by Marius!
Update: added some links for further reading
To my knowledge the actual List Threshold is only available at the Web Application level (best explanation here http://nickhobbs.wordpress.com/2013/06/13/sharepoint-2010-list-view-threshold-explained/), but not List level (you can though Exempt your list from being throttled using this http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.splist.enablethrottling(office.14).aspx - requires Farm Addministrator to set this property - also find explanation of these options here http://msdn.microsoft.com/en-us/library/ff798465.aspx)!
You can also programatically override this in your Query or use best practices and design your query to use Content Iterator (http://msdn.microsoft.com/en-us/library/ee557257(v=office.14).aspx and example http://prasannabj.blogspot.ch/2013/04/handling-large-list-with-content.html)