Limit O8 Concentration

[phillydilly]

Hey,
over the last week i've made the switch from Holdem to O8 for some bonus clearing. In my play, I've noticed that my play has a drop off after 2 hours of multitabling, and a dive after 3 hours. Is this just due to getting used to the game, or does O8 take more concentration hence less time till your 'A' game slips. When playing holdem, it would be 4 or 5 hours before a drop...

How long do you guys play for, and any tips for keeping a high level of concentration?>