FYI, if you hold triangle+cross once the render window comes up, pick the top option twice to use progressive mode. This way, you don't have to use the render plugin's deinterlacer, which makes it look quite pretty (no scanlines or blurriness)
@Masu
This will help with the vibrating. As for slowness turn on some speedhax.
@Sabator
Software mode is inherently slower than hardware mode. If you have multiple cores (read, 3+, although 2 might work) try increasing the number of rendering threads. As for the white boxes, it might have to do with texture filtering, but play around with that 8-bit texture option, too.