Finally sucked it up and replaced our worn out water pressure regulator. Installed a shut off valve as well so I don't have to shut the water off at the meter every time.
The old copper with globs of solder is not mine. Whoever installed the water lines when this house was built should not been allowed near any tools, ever.
Case in point:
The previous owner of my home replaced the pressure regulator, but just installed it next to the old one. What happened was when certain taps were running together, a water-hammer developed between the pressure regulators and made an unbelievable roar and racket. It sounded like the house was trying to get up and run away.
They installed the new one in parallel with the old one? That seems like a terrible idea.
The ole "this one leaks so just solder another onto the end" trick.