Operating system: Windows 10 64bit
Graphics card: NVIDIA GeForce GTX 760
Worked: blender 2.79
Short description of error
The performance of the sequencer is just downright terrible with every build of 2.8 that I've tried.
I've got a default scene with a cube animating from side to side, normal playback is fine, but when I add it as a scene strip in the sequencer it runs at 1fps. And I'm talking Eevee Solid mode. If I change the preview window to Rendered mode (Eevee again) it tanks the entire operating system.
It just seems completely unusable. Is this the case for everyone else? I can't find anyone else complaining about the horrendous performance, yet every version of 2.8 that I've tried has had this issue.
Video files don't run very well in the sequencer either (around 10fps), but it's a whole different level of awfulness with scene strips.
I haven't had much experience with the sequencer admittedly in 2.79, but just a quick compare and contrast - the exact same sequence runs at 60fps in 2.79.
Also note that I am using Blender 2.8 with default factory settings.