CPU chokes to 100 when rotationg bones!

I have a problem with frame 1 and 2 which makes Blender hang for a second to catch up. Something is eating the memory there which makes it impossible to check a looping walk cycle to see the quality of it.

What can I look for?

The project is not very big. Just some disabled walls and a character that is the only thing visible.

Seriously, here is an update:

I added a few 2048px textures to a small object in the node editor, nothing special, and now Blender maxes out the CPU trying to play a walk cycle in the editor!! Rotating and moving the view in the editor is fine, but I can’t rotate bones without activating all of the processor and everything grinds to a halt.

No matter if I use CUDA or CPU, on play it bangs up to 100% and gives 0.34fps in editor.

What is eating my memory?
All problems started after installing a GTX 970…

EDIT: well, not memory at all but processor power…