Extreme lag on a used 2011 MacBook Pro I bought for my parents. Intel Power Gadget shows CPU is running at 800mhz with no fluctuation. Zero. Booted into diagnostics and no problems were found. Can't return it.
what is the temperatures when the machine is running?
Since this is presumedly newly bought, is it a clean install?
What is the battery status?
Clean El Capitan install on a new SSD. No battery - only used as a desktop. Strange, temperature is 64°C (149F) on Amazon Prime Video ~50% load and streaming Xfinity (Flash) using ~85% load and extreme lag.
Yep, the battery acts as a power reserve to provide burst energy when needed (not often) the machine will throttle to prevent draining more than can be provided by the adapter.That's the problem. The machine throttles the CPU back significantly with no battery installed.
What do you mean by original battery?Has to be an original battery I think, otherwise it will keep throttling. Lost a couple of days over this just a week ago, before figuring it out.