Note 12.2 lags, force closes, and random reboots

I just received my Tab 12.2 from EBay today and it lags horribly. Every time I go to different menus, it lags then force closes. I'm on the COI1 build and I have never experienced lag on TouchWiz since the Galaxy S2. Did everyone have this issue or should I contact the seller and ask for a refund?

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