Why does CKFinder load slowly and/or hang when opening?
Knowledge Advanced (all versions), CKFinder
CKFinder generates thumbnails for images in real-time when it’s initially opened and each time you navigate to a different folder. For this reason, if more than 100 images are stored in a folder, that folder will load slowly. If there are many more than 100 images, the CKFinder may even seem to freeze or hang.
To avoid this issue, avoid storing more than 100 images in any single folder in CKFinder.