If I ran feh -t in a directory with lots (more than a thousand) of images, feh opens very narrow and tall window with tiny previews, which is totally unusable. For a directory with 1160 images it looks like http://ompldr.org/vZnhhOQ
I just ran feh -t in a directory with 2000 images and it works fine. Which feh version are you using? Did you try setting --limit-width? Is your window manager doing weird things? Also, it looks like ompldr scaled down your image.
% alias feh
feh='feh --fullscreen --scale-down --sort filename'
That was the trouble, I'll just make another alias.
This is a minor issue, though: Just like --fullscreen, --scale-down should not affect the thumbnail window itself, only images opened from it. It will be fixed in the next release.
Do not apply --scale-down to a thumbnail window (#106)
That's nice, thanks!