I have written one FORTRAN program in my entire life, back in 1991 when my first job included supporting a PRIME minicomputer. When we got a Solaris server later that year the terminal I used was only line oriented so I couldn't use vi and learned ed instead. I only started learning vi properly a few years ago. Old habits die really hard.
One of the scientific staff ran environmental simulations written in FORTRAN that took a week to run. When he ported it to SunOS it speeded up massively, so he just dialed up the detail level of the simulation so it still took a week. As of a few years ago they still used that simulation, and may still do so. I don't know how long it takes to run now though.