Great! Glad that fixed it. Recently a few customers have reported excessive CPU and RAM usage when using the App Store version of Dropzone but switching to the non-App Store version always seems to fix it. I'm not really sure what's causing this but I will be investigating further.

Updates will happen automatically on the non-Mac App Store version so I recommend you just stick with this version. I doubt this is a wider issue with the app store affecting other apps. Probably it's some rare configuration of Dropzone and OS X or other apps that doesn't work well with sandboxing for some reason.

I find it unlikely that my system would be having any sort of performance issues given its capability - but I did disable animations. No dice.

Then I restarted and tried to use Dropzone again. Still incredibly slow...

Fully uninstalled the Dropzone that was downloaded from the App Store and reinstalled using your link. This worked. I now feel comfortable enough to play with Dropzone and add some user actions. If I have more performance issues, I will update and let you know. Thanks again!

Also - what are the implications here? Should I not trust further updates from the Mac App Store for Dropzone? Is there some larger issue with the App Store that I haven't heard of before where your uploads are corrupt? Any idea what the issue is the with App Store versions?

Thanks,
-Steven

If the problems continue I would recommend downloading and switching to the non-Mac App Store version and see if this makes a difference. You can download this version from https://aptonic.com/dropzone3/latest

Your setup actions and settings will be transitioned to the this version automatically. You should close your App Store version and move it to the trash then replace it with the one from the link above. It should detect you purchased on the Mac App Store and register automatically.

Also, another idea that could improve performance is to disable grid animations in the Dropzone settings (click the white settings gear in the top right of the grid and then click Preferences and untick the Animate grid opening and closing box).

System info: 15" rMBP w/ Intel Iris + NVIDIA GT 750M
Suggested app interactions: VirusBarrier? LittleSnitch?

No idea what is going on here, but it is definitely making the app unusable. Very disappointed right now.

EDIT: I have noticed that once it "loads" and the window pops up, then I can use it productively for a little bit. Then if I do other things and try to drag something up there again, there is a huge delay.