I used a MBP with 4 GB of RAM up until 2018 for rather heavy duty data science workloads. Wasn't ideal, but one thing I learned was that you really can't infer

I used a MBP with 4 GB of RAM up until 2018 for rather heavy duty data science workloads. Wasn't ideal, but one thing I learned was that you really can't infer the amount of swapping and performance degradation that occurs just by looking at how much RAM is in use vs. how much you have, because the OS will eat up whatever it gets. The little memory pressure graph you can see in Activity Monitor is quite good, and on my current machine with an "unfortunate" 16 GB of RAM, memory's always full but I have no complaints about speed whatsoever.