Hi Guys,
I was getting the same problems here in my test environment and you will never believe how I solved it.
I had two accounts: bert and ernie
Bert was loggin on immediately < 1s
Ernie was taking on average between 5-10s
The only difference between the two accounts was that Bert had an email address specified on the WIldfire server
So I added an email address to Ernie and now they both login in < 1s
Go Figure???