i have the exact same experience but whilst editing on Fina Cut Pro X (latest version), ie great footage in the raw files from the SD card, but when rendering final movie film get choppy

happy to provide sample files if you give me an adress to upload

//Peter

Slippy Posted at 5-13 01:29
I had this issue.... sussed it this morning... when saving to iPhone it saves via the ‘slow mo’ app... when saved to phone go to edit and you will see as when trying to set the slow mo length... close the the gap and save clip...
FIXED

Thanks man! You really saved my life

I can confirm that when the movie is exported, the middle of the movie is rendered in slow motion (see attached picture).

The solution was indeed to edit the movie and reset the speed to normal.

This happened to me on my iPhone X running iOS 12.1.

Even though there’s a workaround, I wish someone at DJI would fix it.

What sets this off in my case is changing video speed and using curve mode. Have yet to try the workaround this bug.

As noted above, turn off Bluetooth and the video generates perfectly.  

fansfa9d3e71 Posted at 2018-8-7 11:28
I was having the same issue (have a post on here about it somewhere within the last 2 weeks). My fix was to use airplane mode when using the editor. Specifically, I found that if Bluetooth was on then the video was choppy. Going to airplane mode and ensuring Bluetooth was off, the video creates perfectly.

It's kind of weird but it worked.
Here I had to get in the edition with the wifi (or data) on and turned it all off before exporting, set in airplane mode with bluetooth off as well.

Restarting phone and/or removing transition were not a fix here. This was the only solution so far.

Same issue with Samsung s9+. Turning off WiFi and BT didn't help...

Slippy Posted at 2018-5-13 01:29
I had this issue.... sussed it this morning... when saving to iPhone it saves via the ‘slow mo’ app... when saved to phone go to edit and you will see as when trying to set the slow mo length... close the the gap and save clip...
FIXED

tried with airplane mode on with everything off (BT\WIFI\etc)
the same choppy result...

a bit frustrated - the app does not give an option to choose the quality or FPS.
if someone have other ideas or solutions Ill be happy to hear about it

Slippy Posted at 2018-5-13 01:29
I had this issue.... sussed it this morning... when saving to iPhone it saves via the ‘slow mo’ app... when saved to phone go to edit and you will see as when trying to set the slow mo length... close the the gap and save clip...
FIXED

This worked! Thanks a bunch! I tapped on the video clip that was saved on iPhone gallery, tapped on edit, and dragged the sliders to connect. The slo-mo (laggy) part is resolved!

Eric Los Banos Posted at 4-12 01:26
This worked! Thanks a bunch! I tapped on the video clip that was saved on iPhone gallery, tapped on edit, and dragged the sliders to connect. The slo-mo (laggy) part is resolved!

Hey,

Is there Still no fix for this?

I tried the airplane mode, it didn’t work for Me.. now for the Edit option.. I am Not sure what you mean.. I click on edit and then what do I do? See screenshot attached..
Thank youu for the help..

Wint this be an issue to be addressed by DJI? For me on my iPhone XS Max it’s the same problem. I then work with iOS moments with there smooth video editing tool, but it can’t do the things DJI go 4 video editing tool can. This just bothers to many people after so long it it still not fixed. Weird... and the switch of Bluetooth and of WiFi on the phone does not work for me. The rendering simply stops after halve way.. well, at least the make good hardware ;). But the DJI developers are not that good I thinks.... it would be weird if they did not notice this already, right?

I've had the same issue since I've bought my Spark last year. The Internet if full of people complaining about it...
My solution:
I use Splice and Quick from GoPro to edit both my GoPro and DJI footage. I was planning on buying a DJI Osmo and I decided to go for the GoPro 8 coming up this fall.  
Hopefully GoPro won't lock these amazing apps so we can continue using them to edit DJI videos.

I have same problem

October 2019 and i just had this issue too - havent had any issues before - outputted ALOT of vids on iphone xsMAX - this video output felt like it was 15fps. Unusable especially as it also had a hyperlapse so that looked like absolute mud!  
I had a few video colour/grading tweaks, i had a few stills - took them out though.  I usually just use the video captured from the flight but i happened to download the full res vid from the drone so i put it down to that being a much bigger file - i tried outputting 3 times - same 15fps... i packed it away and came here - just tried again a few days later and it spat it out just fine! all good and normal.... strange! the project was still in the app - so apart from the phone probably having a restart / nothing changed and it just worked.

Simple solution I use on my iOS device: I do a 'screen grab' (screen recording with sound) while doing a full screen preview in edit mode in DJI Go 4.
Happy 2020.

Hey,
I had exactly the same problem.
Today I was able to solve it.

A previous reboot of my iPhone 11 pro didn't solve the issue
Someone already mentioned it to close all tabs.
After I did it I restarted the export.
It was really fast exporting the video compared to several tries before.
Now, video is running smooth

I had a similar behaviour in the safari browser before.
It seems that scrooling was laggy.