Using an Ultimaker 2+ with standard settings for PLA Cura version 4.13 out performs version 5.1. Version 5 and 5.1 have been a big step backwards for me so I'm still using 4.13 at the moment. I have attached an example. The terrible print is 5.1.
I'm getting elephants feet, the lettering does not work on the print, probably the Z hop setting and on other print fill issues.
The material used here is Matt PLA, its quite grainy, but I am having the same issues with any PLA and Cura 5.1