Hello - I present here (download) a demo test project that is rendering via Workbench renderer.
With a blank config directory and the almost-latest beta 2.80, it renders in the viewport at “Rendered” shading setting at a smooth 30fps (6GB GTX 1060 / i7 4770k 16GB RAM), which comes to ~.03 seconds per frame. But when I render the animation, the per-frame render time jumps up to ~.3 seconds, which seems strange to me.
This is with no anti-aliasing, and it’s writing out uncompressed PNGs to a RAM disk (my /tmp is RAM), but changing destination to SSD or HDD makes no difference.
Worse, the actual total time between frame rendering starts is ~1.1 seconds (a factor of 37X compared to playing in the viewport). This means that the simple 250 frame animation that plays in 8.3 seconds takes 4.5 minutes to render!
I hesitate to call “bug”, but this seems like a really big jump. Both the frame rendering time of .3 seconds and the strangely large overhead between frames (an additional .8 seconds) seem unnecessarily high.
Not a big deal for a little project like this, but my 10m motion graphics videos are taking all night to render, and it’s bumming me out. 
Am I missing something? An optimization I should know about? A good explanation for the delay? Thanks!