iPhoto library on USB2 harddrive connected to time capsule

Hi,

I've recently transferred my iPhoto library to my external harddrive connected to my time capsule. The performance has dropped dramatically and while I expected a little sluggishness compared to having the library on my laptop, it is now so slow it's not worth it.

The transfer of riles to the harddrive is acceptable and playing iTunes off the same harddrive is seamless.

Is there anything I can do to improve the performance of iPhoto?

Thanks