Slowness while logging via domain account

Slowness while logging via domain account

I am having a problem accessing servicedesk via domain account. it takes long time to log in. however when I logged in using local account, it goes fast.
nothing was changed in active directory and everything was perfect but last week we started encountering this problem.
we are running SD+ with build 8109 in virtual server with Win2008 R2 Ent.
I am restarting the server twice a day and end users are complaining 

attached is the support file for your kind review 

Please help it is urgent 

Thanks

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