Do MTS files need to be optimized?

So i just had some footage shot remotely from a crew that shot on Sony cameras. They delivered the video in several MTS files and I imported and started to edit. Wasn't sure whether I needed to, but after import I optimized the footage in FCPX. It seems after I optimized the footage is giving me a lot of beach balls in FCPX. I don't know why but it seems to chug now.

So overall question: Do I need to Optimize MTS files? Does it benefit me in any way? For reference I am working off a USB 3.0 Lacie Rugged Drive and my machine is a 15" MBP Retina.

Mts doesn't really give enough information, but most probably it's better to optimize this media.

Sorry, I didn't realize MTS wasn't specific enough. I believe he shot with a Sony FS 700, but unfortunately the info on the file doesn't tell me any more info than that.

If you're optimizing, and if it is a lot of clips, you could have background trancoding process going on still. Can you open the background process window, and verify there are none running?

MTS (any source) is highly compressed, so things such as transcoding upon export, rendering, and playback could suffer. Also, for compositing and color grading, that highly compressed media may not hold up as well. The ProRes optimized media should give you better performance, once the optimizing transcoding processes are finished.

Tom Wolsky wrote: Mts doesn't really give enough information, but most probably it's better to optimize this media.

Tom, in the last post in this thread I asked a similar question and you said optimization of AVCHD (ie .mts) was generally not needed: www.fcp.co/forum/4-final-cut-pro-x-fcpx/...5-avchd-vs-mp4#42469

You were right, at least on my 2013 top-spec iMac and Pegasus R4 disk array. FCP X does fine (performance-wise) on most highly compressed material, although there's the potential issue of quality on color correction.

As you described in your book "Final Cut Pro X: Beyond the Basics", optimizing AVCHD media on a system with a slow hard drive can actually hurt performance (great book, BTW). The OP's hard drive is USB 3.0 (probably 7,200 rpm), I/O is probably OK, so reason for the slowdown seems mysterious.

Can the OP mojomikefsu run BlackMagic disk test on the external drive and see what the I/O performance is? If there's any chance it's performing at USB 2.0 rates, that might cause a problem.

Thanks Joe.