200 megabits footage playback issue in FCP X 10.1.1

Hi there

I am having a slight issue with my footage and FCP X 10.1.1. I recorded a couple of cooking inserts using an Atomos Ninja Prores HDMI recorder because I was not happy with the compression of the native AVCHD of the cameraman's footage which is only 25 megabits. I recorded directly to Prores 422 at 200 megabits.

I have brought it into FCP X and am cutting with proxy not sure my i5 core iMac with 16gig of ram could handle it. Playing forward on the timeline is no problem but when I stop and reverse playback to find my cutting point I get a spinning beach ball. This happens with both the proxy and original/optimised media. I have also closed all other programs to maximise resorces to FCP X.

I have cleared the preferences and am only working in one library with three events. I would really like to avoid transcoding the already Prores footage to a lower resolution - any suggestions?

Thanks.

Sounds like a slow drive. What drive/connection are you using for your edit drive?

I am using a USB 3 drive through my Thunderbolt dock. Speed test pic attached. A bit puzzled why the proxy and original media are acting in the same way.

The rest of my edits have no problem.