Crawl error Processing this item failed because of an unknown error when trying to parse its contents sharepoint

During various search troubleshooting i came across the following crawling error in the Crawl log of a SharePoint 2013 environment.

Processing this item failed because of an unknown error when trying to parse its contents. (Error parsing document ‘http://********.*****.com/Project/abcd/Q_M/ABX/SitePages/Homepage.aspx’. Sandbox worker pool is
closed.; ; SearchID = *******************)

In order to fix this you can try to perform the following action plan:
Open “Local Policies
Click on “User rights assignment

user-rights-assignment

Make sure that the search service account has the following rights:
Replace a process level token

adjust-memory-quotas-for-process

Adjust memory quotas for a process

adjust-memory-quotas-for-process-properties

Impersonate a client after authentication

impersonate

Please make sure that the policies don’t get changed afterwards.

After implementing the above changes please run a clear configuration cache
After clearing the cache, start a full crawl and the errors should be gone.

Start SharePoint Service Application Proxy using Powershell

If your Usage and Health Data Collection Proxy is in a stopped state here is a quick bit of PowerShell to to get it started:

$sap = Get-SPServiceApplicationProxy | where-object {$_.TypeName -eq “Usage and Health Data Collection Proxy”}
$sap.Provision()

The above can easily be adapted to allow you to start any Service Application Proxy

Slow SharePoint improve performance without upgrading hardware

what you can do if your SharePoint is sometimes very slow.

E.g.: on the first start of a Site
Sometimes during the day a search query will take about a minute until you get results…..

Just look on that article: http://support.microsoft.com/kb/2625048

it will improve “feeled” performance (site response times) massive, if you’re going to implement both solutions.

Disabling CRL Check is just necessary if the SP Server does not have internet connectivity, that means proxy settings must be configured for the server itself

http://technet.microsoft.com/de-de/library/bb430772(v=exchg.141).aspx, and your proxy must allow traffic from the server of course.