Why do the Image Capture Extension and softwareupdated processes consume so much memory?
Since I upgrade my late 2009 iMac (4GB memory) to Yosemite, the system had not been performing well. It would be slow at time particularly after it had not been rebooted for a a day or more. In the Activity Monitor I noticed the it Image Capture Extension was steadily growing to become a major user of memory, and the memory pressure was in the yellow as the extension used more memory. I could not determine what program or process was causing this. I then installed two 4GB memory boards increasing my memory to 12GB. Now the Image Capture extension stays at a low value (25-50MB) and does not grow, and the memory pressure stays in the green. Memory is now cheap, your 2GB is likely your problem.