In a web app, we're looking to display a list of sam accounts for users that are a member of a certain group. Groups could have 500 or more members in many cases and we need the page to be responsive.

With a group of about 500 members it takes 7-8 seconds to get a list of sam accounts for all members of the group. Are there faster ways? I know the Active Directory Management Console does it in under a second.

I've tried a few methods:

1)

PrincipalContext pcRoot = new PrincipalContext(ContextType.Domain)
GroupPrincipal grp = GroupPrincipal.FindByIdentity(pcRoot, "MyGroup");
List<string> lst = grp.Members.Select(g => g.SamAccountName).ToList();

2)

PrincipalContext pcRoot = new PrincipalContext(ContextType.Domain)
GroupPrincipal grp = GroupPrincipal.FindByIdentity(pcRoot, "MyGroup");
PrincipalSearchResult<Principal> lstMembers = grp.GetMembers(true);
List<string> lst = new List<string>();
foreach (Principal member in lstMembers )
{
    if (member.StructuralObjectClass.Equals("user"))
    {
        lst.Add(member .SamAccountName);
    }
}

3)

PrincipalContext pcRoot = new PrincipalContext(ContextType.Domain)
GroupPrincipal grp = GroupPrincipal.FindByIdentity(pcRoot, "MyGroup");
System.DirectoryServices.DirectoryEntry de = (System.DirectoryServices.DirectoryEntry)grp.GetUnderlyingObject();
List<string> lst = new List<string>();
foreach (string sDN in de.Properties["member"])
{
    System.DirectoryServices.DirectoryEntry deMember = new System.DirectoryServices.DirectoryEntry("LDAP://" + sDN);
    lst.Add(deMember.Properties["samAccountName"].Value.ToString());
}