How to reproduce:
1. Open the attached project ("Shadergraph Animation Tests.zip")
2. Enter Play mode and let the animation play out fully
3. In the project's directory, open the Recordings folder and add them to any video editing software (Davinci Resolve used in this case)
4. Preview the added clip and observe the video

Alternatively, the speed mismatch can be observed when outputting as a "Movie" as well with these steps:
1. Open the attached project ("Shadergraph Animation Tests.zip")
2. Click on the "Timeline" object in the Hierarchy Window
3. In the Timeline Window click on the RecorderClip and change its "Selected recorder" setting to "Movie"
4. Enter Play mode and let the animation play out fully
5. In the project's directory, open the Recordings folder and observe the "movie.mp4" clip

Expected result: The recorded animation is exactly the same as in the Editor's Scene View
Actual result: The recorded animation's speed slows down at times for the "Movie" setting and speeds up at times for the "Image Sequence" setting

Reproduced in: 2019.1.0b2, 2018.3.5f1
Couldn't test with: 2019.2.0a4 (due to multiple errors)

Note: Editor also occasionally crashes on UnityEngine.ScreenCapture:CaptureScreenshotAsTexture when the "Selected recorder" setting is set to "Image sequence"