Well, it seems that your soundbridge firmware is outdated.
Also, what version of firefly / mt-daapd are you running ?
I can just second Ron. RSP is *much* faster. I have a roku SB and use firefly for a few months now to stream music to my SB, works like a charm (most of the time, anyway) 😉
Try to check your SB for firmware updates, or to do the beta firmware thing, if there is any.