Speed plays a roll, also expirament with the default curve size and curve size at each WP, seems bigger helps unless you have a sharp turn to make at a WP. Then it's a matter of editing.
I've been experimenting with Litchi and I've got it pretty nice and smooth. I'm happy.
Personally, I find the Cable Cam on 3DRs Solo to be a great and convenient feature. Now with Litchi, I've got a very good Cable Cam method working, that's almost as easy and convenient as the Solo's version, but has some added benefits/features. I still need to tweak some of the settings to get it up to the Solo level, especially at higher speeds, but it's **** good and I'm confident I can tweak it until it's as good or better. Plus you get all the other benefits of Litchi.
If your interested in Cable Cam, in the Litchi manual online, there is a "cookbook recipe" for creating Cable Cams. It's at the end of the waypoint section. The main thing it has you do is assign button C1 to create a waypoint at current location. So with this it's almost as easy to setup as a Solo. Switch to waypoint mode, fly somewhere yaw and tilt your gimbal to frame the first shot, click C1, move to next waypoint, frame your shot, hit C1, and keep going. When your done, just hit play. While its playing you can use the right stick to speed up the P4 on the cable, or slow down and even reverse to run the cable the other way. When you let go of the stick, the P4 reverts back to the default mission cruising speed.
And the great thing is that when you are done, you've actually got a waypoint mission that you can go back into and edit. So you get the power and convenience of Cable Cam, and you also get a fully *editable* mission.