Information on the XML Service

Greetings MusicBrainz community,

I've been working on a program that uses the XML Service to search for information on music and clean their tags.

For now the system works like this. I will use Metallica as an example.

1.Generate a list of potential artists from the file's meta information and the filename itself.

2.Search them on MusicBrainz and take the best result with its ID.
   (Example: http://www.musicbrainz.org/ws/2/artist/ … metallica)

3.Use these Artist IDs to do another search in which I find all the releases of said Artist. Keep in memory only the releases of type 'Album' from the US and CA with their IDs.
    (Example: http://www.musicbrainz.org/ws/2/release … ountry:US)

4.For each release ID, I get a list of the recordings contained in it.
    (Example: http://www.musicbrainz.org/ws/2/release … ecordings)

5.Search for matches, etc.

It works quite well, but the problem is that it takes quite a lot of time. I have the program setup to follow the rate limiting rules. I was wondering if there was any way to optimize the searches I make or if what I'm using is the only way to go?

Like, is it possible to get the releases of multiple artists at the same time? Or get the recordings of multiple releases at the same time? Cutting down the amount of searches I make would trememdously lower the time it takes for each song to complete a search.

Any help is welcome!
Jonathan