An old laptop will run any Linux distro flawlessly and be equally snappy (as in, low-latency disk reads, fast boot times, many applications open) as a current-gen one if you put in a fast SSD and max out the RAM.
I know that this topic is controversial, but it strikes me as odd how many people seem to equate software engineering with a monster laptop, when many of us get lots of work done on smaller, less beefy client devices, offloading the real heavy lifting to a machine that can handle it.