Operating system: Windows 10 64 bit
Graphics card: Nvidia GeForce GTX 760
blender2.8, 2018-12-13 01:30
Short description of error
This is a general problem that cannot be defined by a specific scenario.
Animations created and played in Blender 2.79 run @ smooth 30fps.
In Blender 2.80 they run @ 5fps.
In general it is just much much slower than 2.79, to the point of making it unusable for even short simple animations.
Changing viewport settings and user preferences make no difference.