Editing Lag Issue - I Need Help!

Hi Guys,

I'm a high school media student and am currently editing the footage for my major folio piece. However I've encountered an error while editing; as soon as more than one clip is added to the timeline, playback becomes laggy. As you can imagine, this makes work very tedious as I can't view what I've edited.

I was wondering if anyone here had any suggestions on how to resolve this issue. These are the things I have already tried:

• Storing all the raw footage on an external hard drive with USB 3.0
  • Attempted to transcode all the raw footage with the transcode option in FCP. However this didn't work; it would load 2% then begin again
  • Closed all processes except the necessaries with Activity Monitor
  
  All my footage is shot in 1080p and is saved as mp4 files. The amount of footage only amounts to just over 4 GB worth of data. My MacBook - which I am loaning from school - has a 2.3 GHz i7 processor, 8 GB of RAM and a 384 MB Intel HD Graphics 4000 card.
  
  Any suggestions would be greatly appreciated, since I have just over a week to finish editing my film!

Check your drive is actually mounting as USB3: Apple menu → About this Mac → System Report → USB. You're looking for your drive under a heading 'USB 3.0 SuperSpeed Bus'. If it's under 'Hi-Speed Bus', it's mounted as USB2.

There are several possible reasons for that. Some Macs set the USB port to whatever standard the first device plugged in was, in which case a restart should sort it out.

I've recently had a situation where my sole USB3 device (a FirmTek miniswap/U3 - excellent piece of kit, by the way) dropped from ~300Mb/sec to more like 20Mb/sec, with lots of beachballs. Turned out to be a bad USB3 cable.

Another useful test would be to run Blackmagic Disk Speed Test against the drive. You'll find it in the Mac App Store. For a USB3 hard drive I'd expect upwards of 80Mb/sec read/write.

Your Mac should be capable of handling the compressed media without issue – HD4000 graphics isn't the best news, but it should be usable. That's what leads me to think that it's your drive throughput that's the issue. USB drives are rarely ideal, but I've happily cut off my Miniswap on several occasions.