My kids accounts are agonizingly slow.

I purchased a brand new computer yesterday.  I have only installed MS Office besides the Norton products with no prior version of anything.  I have three user accounts (one for me and two for my kids).  My account is not linked to Safety Minder and the internet works perfectly.  My kids accounts are agonizingly slow.  Most of the time they do not load and say the server is busy.  I have tried both wireless and wired internet connections with same results.  Windows 7, ie9.