[Win32Exception (0x80004005): The wait operation timed out]

Stack Trace:

[Win32Exception (0x80004005): The wait operation timed out]

[SqlException (0x80131904): Connection Timeout Expired. The timeout period elapsed while attempting to consume the pre-login handshake acknowledgement. This could be because the pre-login handshake failed or the server was unable to respond back in time. The duration spent while attempting to connect to this server was - [Pre-Login] initialization=55; handshake=14983; ]
System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection) +347
System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource'1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection) +78
System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource'1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection) +191
System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource'1 retry, DbConnectionOptions userOptions) +154
System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource'1 retry, DbConnectionOptions userOptions) +21
System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource'1 retry) +90
System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource'1 retry) +443 System.Data.SqlClient.SqlConnection.Open() +96
System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure) +41

[EntityException: The underlying provider failed on Open.]
System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure) +207
System.Data.EntityClient.EntityConnection.Open() +104
System.Data.Objects.ObjectContext.EnsureConnection() +75
System.Data.Objects.ObjectContext.CreateFunctionObjectResult(EntityCommand entityCommand, ReadOnlyMetadataCollection'1 entitySets, EdmType[] edmTypes, MergeOption mergeOption) +43
System.Data.Objects.ObjectContext.ExecuteFunction(String functionName, MergeOption mergeOption, ObjectParameter[] parameters) +310
System.Data.Objects.ObjectContext.ExecuteFunction(String functionName, ObjectParameter[] parameters) +57
DoktorSibelUsta.db_SibelUstaEntities.sp_makale() in D:\Seda Projeler\DoktorSibelUsta\DoktorSibelUsta\SibelUstaDataModel.Designer.cs:463 DoktorSibelUsta.Default.Goster() in D:\Seda Projeler\DoktorSibelUsta\DoktorSibelUsta\Default.aspx.cs:24
DoktorSibelUsta.Default.Page_Load(Object sender, EventArgs e) in D:\Seda Projeler\DoktorSibelUsta\DoktorSibelUsta\Default.aspx.cs:16
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51 System.Web.UI.Control.OnLoad(EventArgs e) +95
System.Web.UI.Control.LoadRecursive() +59
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +678

I have two questions and need quick resolution for the issue :

1. drsibelusta.com - website that has the issue works very slowly
2. sometimes we have such application time out error

Please advise me how I can resolve such issue and have such site works quikcly and no issue occurrence