Thanks for sharing your thoughts. Some of these suggestions are in the combination of this suggestion: Call for Content: Workspaces
Like a one button to set up in the file browser to set up the scene/sequencer/timeline properties for best performance for the casual/newcommer user. The button could be enabled when a clip is selected, so the data from this clip could be extracted for the setup of VSE settings.
On colorspace, 2.8 has a lot of colorspace/colorhandling options. The default 2.8 colorsetting gives me a 1.4 FPS playback of 720x480 footage. So a mismatch will give very bad FPS.
Preview area, I’m just thinking that new users will be puzzled by only being able to view the first 250 frames, as standard NLEs do not have a limited preview area set as default. Maybe the preview area should be optional and the default setting should be off?
Render Percentage Scale, does work like a render free proxy in 2.79, where a lower setting will give a better playback rate in preview. Seems odd, but it does…
Rendersettings, if you’re an advanced user I can understand why you would want to render pngs without sound, but for casual users/ newcommers they would, I guess, prefer a video-file with audio, ready for YouTube or Vimeo upload.