Trying it here, Windows 10 current, Nvidia 1060, GPU-only, some numbers:
2.80 beta (current, self-built): 5:59.
Both showed virtually identical CPU and GPU utilization. I messed around with a bunch of things without finding any smoking gun that would explain it being so different.
I next tried fishy_cat (30 samples progressive GPU only, post-processing disabled) and got 0:34 in 2.79 and 1:34 in 2.80 which also looks pretty bad.
For these scenes progressive render appears to be substantially slower in current Cycles than 2.79a, and maybe that’s worth investigating more.
I know progressive render can be a nice way to preview a scene, but you can also have this (below) in 30 seconds with tiled rendering and denoise, or even real-time with Eevee depending on what you’re doing.