I just saw a presentation on UVM tips and it recommended to NOT use the uvm_field macros. Several companies have come out and said that these generate large, cumbersome methods that are hard to debug, and that you should write the methods yourself. IMHO, this seems like bad advice. Having written these methods for VMM, I find it error prone and a waste of time. Why spend 10-20 minutes creating these when the macros do it automatically? Once you waste an hour debugging the copy method when you leave out one variable, you stick with the macros. And how slow are these automatic methods? They never show up on the simulation profiler.
This reminds me of when I used to change the oil on my car, and then left a rag on the engine that caught fire and cost me $200 to replace the O2 sensor, and could have ended up much worse. How much was I saving?
It is your time that is the most valuable thing. Use the macros to save coding time and debug time. Spend your time on something creative like understanding Flits!