I'm willing to overlook the bugs such as the same item appearing more than once in a feed (it's quite new), but the incredible slowness of it make it unusable for me.

For example, I loaded it before writing this comment, and as of this point, it still hasn't finished loading. I just get a spinny box and 'Loading...'

I also know from experience that if you click on something else, such as a folder, it won't override what it's currently loading, so the state of the UI will get out of sync.

You also can't read a list of items, you have to read one by one, incurring yet another AJAXy-load which doesn't necessarily ever respond, thus leaving in you in Loading... limbo.

The current layout make it too hard for me to move quickly through a large number of items.

I appreciate the effort but even if it did manage to import my feeds the UI just doesn't work for me.