• Hardware Bottlenecks: You should constantly monitor  system resources on SharePoint Servers and SQL Servers –  CPU, Memory and Disk I/O should all be monitored if any of these are showing signs of strain you should consider upgrading your hardware.
  In most cases – Disk I/O on  SQL Server  is the bottleneck for SharePoint performance and ironically it is often a neglected issues and is frequently not included in performance monitoring.
  One strong tip for SQL Server I/O is to split your databases into dedicated RAID systems, for example: store Content Databases of your application on 4 SAS/SCSI storages in Raid10 mode, and the Search, TempDB (these two are the most I/O consuming) on the even better and faster dedicated storage. Avoid keeping all the databases in one physical hard drive/matrix.
• SQL Indexing – Keep your indexing parameters optimized in your SQL Server Databases. Create and run at least once a week SQL Server job with “Rebuild Indexes” and “Update Statistics” tasks. You can view your indexation and defragmentation state by running ODBC_CHECKDB on the content databases.
• Warm Up your IIS Server – After pool recycling, restarting your IIS Server etc., the front end servers will lose their cached data and all site elements will need to be reloaded resulting in slow performance. Usually the first main page rendering is extremely slow, but there is a way to avoid that. Use Application Warm-Up.
  The Application Warm-Up extension can be deployed in a IIS 7.5 environment (Windows Server 2008 R2 native). This extension pre-loads all the site content before the first user-requests a page from IIS. By preloading the web application, the IIS worker processes reduce the time needed to render the site and respond to the first request. The IIS Application Warm-Up can be downloaded at http://www.iis.net/download/applicationwarmup
• Content Compression – Ensure that Dynamic Compression and Static Compression in IIS 7/7.5 is enabled. This can greatly reduce the network bandwidth requirement which is especially important in WAN wide networks.
• Move extensive farm services to dedicated servers – If you are experiencing slow performance, and you need to improve it at any cost – add more servers to a farm. If you currently have Front-End role and Query, Indexing, Office Web Apps role on one physical machine, It likely that you will experience slow performance on SharePoint sites. In this circumstance you should choose the path to split the extensive roles to dedicated servers, so that the Search Query, Search Indexing, Front End and Office Web Apps will be stored on separate physical machines.

I hope I covered most of the performance tips you can deploy in your farm. Please let us know if you have any additional tips you would like to contribute.

Using SharePoint Resource Throttling you can set the query limits, so the farm will refuse to execute the problematic user actions at certain times. You can set the “happy hour” for those queries to any time you want and instruct your users to contribute with those large lists ONLY at specific time.

To access Resource Throttling settings for your SharePoint site/farm, go to Central Administration > Application Management and select the web application (in our example – SharePoint – 80 application) and from the ribbon select General Settings – Resource Throttling.

Resource Throttling Configuration in the Central Administration Ribbon

Now we can specify numerous maximum parameters, which are  self-explanatory. In this article I will only focus on few of them.

Setting the Object Overriding and Administrative threshold is important here. Why? You can easily throttle queries and therefore improve performance, but in most cases you will still need to access, read and modify some objects from the throttled resources. It’s necessary to have a setting that will allow some selected users to contribute to the throttled resources and override the settings entered. In this way you will avoid often made requests  to the throttled resources, because only a selection of users (from our example) will have rights to perform huge queries.

To set this, ensure that the Object Model Override option is set to “Yes” and that List View Threshold for Auditors and Administrators is set to the maximum number  capable of showing all the content from your portal. The default value of 20000 is a sensible starting point but you will probably need to fine tune this.

Object Model Override and List View Threshold for Administrators settings

Now, set the daily time window for the rest of the users who will also need to access the throttled resources. This may be the time out of  your working hours, so most users will be offline , or early morning, where the traffic is still low. To set this, look at Daily Time Window for Large Queries setting.

In my example, I’ll set the time window from 7 AM to 9 AM, so all early birds will have access to throttled queries

Daily Time Window Settings

Whether to use the FullTextSQLQuery or KeywordQuery class depends on the complexity of the search queries that need to be implemented. FullTextSQLQuery allows for complex SQL queries to be executed whereas using KeywordQuery is considerably more simple – just pass the search terms in basic text format and retrieve the results.

SharePoint Search Using KeywordQuery

KeywordQuery class allows a keyword or a SharePoint property filter to be passed directing to the search service without needing to construct a SQL query. There are only two refinements supported for search using KeyWordQuery. Adding the + sign in front of a word mandates that the results must include that search term, adding a - sign in front of a word will mean that results results will specifically exclude that word.

The KeyWordQuery object is instantiated by passing in the SharePoint site to the constructor, then set the QueryText property of the object to the text you wish to search the SharePoint site for. The ResultTypes property should be set to ResultType.RelevantResults to retrieve the results. Then simply call the Execute method to execute the search. The below example demonstrates passing the results of the SharePoint search using KeyWordQuery to a DataTable.

For example:

DataTable resultsDataTable = new DataTable();

using (SPSite site = new SPSite("http://sharepointsite"))

{
KeywordQuery queryObj = new KeywordQuery(site);
queryObj.QueryText = "sharepoint +search -exchange";
queryObj.ResultTypes = ResultType.RelevantResults;

ResultTableCollection resultTables = queryObj.Execute();
if (resultTables.Count > 0)

{
ResultTable relevantResults = resultTables[ResultType.RelevantResults];
resultsDataTable.Load(relevantResults, LoadOption.OverwriteChanges);
}

} 

return resultsDataTable;

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