Same here! My main change was getting an SSD. If you're in this boat, I highly recommend it. If I wanted to really push it, upgrading to 8GB of RAM would probably make it work extremely well.
It's nice to have things that run well with relatively small changes.
Upgraded mine to 16gb ram and ssd years ago. I also replaced the battery last year. My only wish is to have more cores, but otherwise it's working fine.
I wonder if the current MBP lineups can last 8 years of constant software development use like this 2012 model.
It's nice to have things that run well with relatively small changes.