Are you sure the "task list" has completed all the tasks before moving into Develop or some other processor intensive module? I find that I can work faster than lightroom can keep up ( no surprise there ) and thus putting a heavy load on the system. I'd recommend waiting for all background tasks, like thumbnail building, to be completed before heading into Develop and/or trying to do anything else. I understand it defeats the purpose but, even though it's a background process, scaling and resizing the images will be hitting the same instructions on the CPU as many of the operations in Develop - modern technology should be advanced enough to deal with this may not be the case.
I used to have a lot of trouble with Hyper threading and Shake, using OpenEXR or Cineon files produces a lot of data and doing various image processing tasks would cause the machine to hang because all the processes used similar instructions. Hyper Threading is only useful if you're doing different work in each thread - it's the difference between running while chewing gum, and running while trying to skip.
I apologize that this doesn't actually present a solution, but maybe it'll give you more of an idea of how you could adjust your work flow to avoid frustration.