Web site using using active directory groups slows to a crawl intermittently - active-directory

Question

I have an asp.net mvc web site on an intranet. Access to the site is determined by groups in active directory. There are 4 different groups each having different access in the site. I have been having occasional problems with the site running slowly. The site will run fine for several days then suddenly slow to a crawl. I have both a test site and a production site. When the slowdown occurs both sites are affected equally. I also have a site that test site that has no active directory access and it runs with no problems while these two sites are crawling. The sites I am having trouble are running under a user account because the application has to reach out to another share on the intranet in order to print and merge pdf files. The sites are running under the same application pool. When the problem occurs, all pages are equally slow even pages with no database activity. When the problem occurs I reset IIS, restart the web sites, and recycle the threads. The only thing that actually resolves the problem is restarting the server. Sometimes it takes a additional restart to get the site back to normal. Here are a few things I have tried. It seems the problem is occurring less often but still occurs.
1. Reduce the numbers of times that I query active directory.
2. Reset IIS when the problem occurs. This has not been helping.
3. Recycle application pools.
4. Restart the sql server service
5. Made sure fully qualified names are used when referring to servers. This seems to have reduced the problems some. Not sure though. I am using IIS 7 on a windows 2008 server, 64 bit.
user = ConfigurationManager.AppSettings["TravelCardUser.AD_GroupName"];
approver = ConfigurationManager.AppSettings["TravelCardApprover.AD_GroupName"];
maintenance = ConfigurationManager.AppSettings["TravelCardMaintenance.AD_GroupName"];
admin = ConfigurationManager.AppSettings["TravelCardAdmin.AD_GroupName"];
testuser = ConfigurationManager.AppSettings["TestUser"];
List<string> adgroups = new List<string>();
adgroups.Add(admin);
adgroups.Add(approver);
adgroups.Add(maintenance);
adgroups.Add(user);
this.groups = adgroups;
List<string> groupmembership = new List<string>();
foreach (var group in groups)
{
if (!String.IsNullOrEmpty(testuser))
{
this.username = testuser;
}
else
{
this.username = currentloggedinuser;
}
using (var ctx = new PrincipalContext(ContextType.Domain))
using (var groupPrincipal = GroupPrincipal.FindByIdentity(ctx, group))
using (var userPrincipal = UserPrincipal.FindByIdentity(ctx, username))
{
if (groupPrincipal != null)
{
try
{
if (userPrincipal.IsMemberOf(groupPrincipal))
{
groupmembership.Add(group);
}
}
catch (Exception ex)
{
string theexception = ex.ToString();
}
}
}
}
Here is my ldap connection string.
<add name="ADConnectionString_UserRole" connectionString="LDAP://locationX/cn=TravelCardUser,ou=LocationXgroupsGroups,dc=acme,dc=us,dc=com" />

Answer 1

Ther server slows down every 3 or 4 days so I shut down the application pools to my applications and used Sysinternals to monitor process for 3 days.
http://technet.microsoft.com/en-us/sysinternals/bb896653
I am seeing that processes related to sequal server and team foundation server are grabbing resources but not releasing them. By the way I ran my asp.net code through Red Gate Memory Profiler and there are no memory leaks. Now I have to figure out what to do about the problem with memory usage.