Does no-one else have a problem with Photos loading under El Capitan?
I have the same exact problem, photos hanging for days at 18% complete. I even restored from an old pre-upgrade version of photos library and still the same result.
El Cap also crashes my home Netgear router whenenver I try to access any menu items from any browser (Chrome, Firefox, Safari). Had another laptop running El Cap access my router with the same result. Then tried a Yosemite laptop to access a menu item on my router and it was totally fine.
Looking forward to hearing solutions and explanations of what's happening with photos in El Capitan.