Power output at wall outlets

For awhile, I have been suspicious of the consistency of the power supply from my wall socket. Like a lot of us, my system doesn’t sound exactly the same everyday. Some days, it sounds a little thin. Yes, I have a power conditioner.
Today, I proved my suspicions about my house.
I plugged in my 7 gallon air compressor in the car port. I also plugged in my pressure washer to do my car in a different outlet in the carport.
While the compressor was filling, I began to use the pressure washer. Every time I pulled the trigger on the washer, the compressor would slow down. I did this more than once. My home is about 60 years old, and not all of the wiring has been replaced.
And what effect do my neighbors around me have on my house?
Would anyone disagree that a P3 is a good idea?

It sounds like you’ve got some pretty thin wiring and yes, a P3 would help a great deal, especially when the power draw is dynamic as it is with music.