Mac OS X Hints user macjosch found that their memory cards and cameras were slow to be recognized by Image Capture:
"I thought it fairly strange when Image Capture on all of my Macs became very slow at recognizing photos on cameras and memory cards. The memory cards showed up on the desktop, however, and photos could be copied manually without problems.The issue is because Bluetooth devices seem to keep Image Capture from accessing memory cards and cameras plugged into your Mac. To alleviate the problem, navigate to System Preferences, click Bluetooth, and select and delete the devices you no longer need. According to macjosch, with no Bluetooth phones connected, Image Capture works at a normal speed.
"In the end, Image Capture was so slow that the camera entered power saving mode even before it could be recognized. It all looked like a network timeout to me. The list of shared devices (three Sony Ericsson phones and a Samsung phone) was growing with each outdated and swapped mobile phone -- and of course, they were not available via Bluetooth."