Can you pls. let us know the version number of the application (Help > About Adobe Acrobat Reader). Also pls. let us know if do any operation (comments etc.) on the PDFs or just view/scroll through the document. Also, does the CPU usage dwindle after 2/3 minutes of the operation? If not for how long does the CPU usage stays that high? Pls. provide us the process dump at the time the cpu usage is high.