Foo Gallery Editor Non-responsive

I have a photo gallery that contains 2100+ images. I first set it up about 9 months ago. The page is still loading properly for viewing. However, when I open the gallery editor planning to add more images, the editor is non responsive. It keeps spinning and asks if I want to “wait” but so far it is not opening up even after a long wait. I tested to create new galleries with a few images and they work fine. What should I do? I’ve invested a lot of time to create and arrange the gallery. Please help!