XDCAM and ProRes

I am confused so thought some of you clever folks could help me out.

I know apple officially say that XDCam does not need to be transcoded to prores in order to work in FCPX. As far as I can tell they even say there is no benefit in making this conversion from XDCam to prores at all. Hence I cannot create optimized media from an XDCam file from within FCPX.

However when I do a manual conversion of all my material to prores I see a significant boost in performance. Especially with lang timelines. (More than 30 minutes).

But does anyone know why it is apple keeps saying that XDCam will perform as well as prores when this obviously is not the case? (In my experience anyway)

Thanks

I don't have the answer, but do have a similar situation with my Canon XF100, which shoots a similar codec (mpeg2 50Mps 4:2:2) in a .mxf wrapper. FCPX also will not transcode this to prores - the option is grayed out.

My question is - how did you manually convert your XDCam clips to prores?

I use Sony XDCam transfer which unwraps the mxf to mov. From there I just use compressor to batch transcode the files.