After rereading your thread, I found that I didn't get it correctly in my previous reply.
In your illustration, if you change the text from "b.psd" to "b.psd foo" for example, 2 things will happen simultaneously:
1. Listary will search for "b.psd foo".
2. Listary will continuously load icons for "b.psd" because Listary won't update the view until it has finished searching "b.psd foo" completely.
In fact #1 is the bottleneck here, so you're waiting for the actual search process of "b.psd foo" instead of loading thumbnails. Listary does cancel icon loadings automatically if the view is updated.