var projectCollection = TfsTeamProjectCollectionFactory.GetTeamProjectCollection(new Uri(tfsURL + "/" + collectionName));
var myService = projectCollection.GetService<TswaClientHyperlinkService>();
string wiURL = myService.GetWorkItemEditorUrl(workItem.Id).ToString();

Soultion
Follow the below steps on the build agents
• Go to Start->Programs->Microsoft Team Foundation Server 2010/ 2012 ->Team Foundation Administration Console
• Select a build agent and click Properties
• Change the working directory from to $(SystemDrive) to D:, E: etc depending upon the free disk drive

Explanation:

Perform the following cache clean steps when you see VS – TFS performance issues

Solution:

TFS client cache clean up steps:

• Close all Visual Studio IDE instances
• Close browser or excel instances connected to TFS  
• For Windows XP, delete all content under:

                C:\Documents and Settings\[USER]\Local Settings\Application Data\Microsoft\Team Foundation\

• For Windows 7 or newer, delete all content under:

                C:\Users\[User]\AppData\Local\Microsoft\Team Foundation\

Errors:

TF262600: This SharePoint site was created using a site definition that requires data from Team Foundation Server. However, the site is not currently associated with data for a team project. To ensure that this site functions correctly, you must configure a team project to refer data for that project to this site. For more information, see this topic on the Microsoft Web site: How to: Add a Team Project Portal.

This site doesn't have a default Team Project. You can explicitly select a specific Team Project.
This web part is not configured properly. Click here to configure web part in tool pane.

Explanation

This issue was caused by missing permissions for the [TEAM FOUNDATION]\SharePoint Web Application Services group to the team project. I get into the issue whenever I detach and attach the same collection (side by side) to different TFS App tiers for testing/R&D

Soultion

1) Add and grant READ permission for [TEAM FOUNDATION]\SharePoint Web Application Services group to the affected team projects.

2) use tfsredirect.aspx to refresh the cache

http://SharePointServer/sites/CollectionName/TeamProjectName/
_layouts/TfsRedirect.aspx?tf:type=webaccess&tf:test=1&tf:clearcache=1

Note : This page should not return any errors and the value for TeamFoundation.Temp.LastRefreshDate should include the current date.

3) Repair the connections between TFS and SP

• Open the Team Foundation Server Administration Console
• Expand the Application Tier in question (the one hosting the Team Project Collection and Team Project with the problem)
• Highlight the SharePoint Web Applications node.
• In the SharePoint Web Applications list, highlight the appropriate connection and then click "Repair Connection"

Explanation:

TFS store date & time as the UTC time in DB to work across the regions. Visual Studio will translate the date to the time zone of the client but Web Access follows the server time zone setting by default