The compression scheme won't affect render-time much. And Poser doesn't make use of hardware acceleration, so your killer graphics card won't speed things up, either. The only ways to speed up an animation render in Poser are:

1. Get a faster processor and more memory (not likely in your case)
2. Render at lower quality (turning off shadows, antialiasing, bump maps, textures; disabling transmaps; lower resolution; render using Current Display Settings; etc.)

Cheer up. It could be worse. Poser could have raytracing, like Bryce, in which case that 45-minute wait would become 45 hours.