What is the Issue?

CRM performance becomes very slow. But there is no clue what could be the reason behind slowness of CRM.

The Reason-

There might be several reasons to CRM performing very slow.
-Heavy customization on Entities
-APP Pool issue
-Asynchronous services performance
-Database issue
-Network related issues.

Solution-

Let’s see the solution for slow performance-
1.Heavy Customization on Entities-
-Try to make pages lighter by reducing the function calls on page load.
-If performance observed very slow on any event of some particular entity, check the workflows/plugins execution and try to make them asynchronous if possible. This will definitely improve the performance of your CRM.

2.Application pool issue-
-Sometimes there might be issue with application pool, which needs to be periodically recycled.

3.Asynchronous service Performance-
-This is the another issue which affects the crm performance. Restart the asynchronous service to resume/speedup the pending asynchronous workflows which are causing slowness in some operations.
-you can check here if you are facing some issue with asynchronous services-Asynchronous Processes/Wrokflows Stuck in InProgress/Waiting status in MS Dynamic CRM

4.Database issues-
-This is the common issue MS Dynamics CRM developer faces in a life. Due to heavy data loaded in database the crm might take time to perform operations like creating records, retrieving records, loading the views in some particular entity form. You can create indexes or recreate indexes if already exist, on such a tables which is having heavy load of data.  This will be improve performance more significantly.

5.Network Related issues-
-Very rarely user will face the slowness of CRM performance due to network related issues if they have some complex network structure, which causes the high latency in the network.
-In the case of NLB, slow performance issue might be observed by the CRM Users.In this case the you can check NLB settings.

MS Dynamics CRM provides the inbuilt diagnostics tool. You can use this tool to check point 1 and point 5.  You can use tool like-http://<YourCRMServerURL>/tools/diagnostics/diag.aspx

Another great tool that is built in tool available into CRM (2013 SP1 and up) is the CRM Performance Center. Try this with IE.
To activate,  log into CRM then press CTRL+Shift+Q on your keyboard. Click Enable, then click Refresh. When browsing in CRM, this will capture how long it takes components to load. This is a great alternative to tools like Fiddler and won’t require you to install additional third-party tools.

You can also refer-
Optimizing and maintaining client performance for Microsoft Dynamics CRM 2011 and CRM Online

Hope this will help you…