I also put an SSD in my 2009 MBP - in 2011! It was $500 for a 256gb drive and it was worth every penny.
Even though that drive is slow and expensive by today's standards, I don't know if it ever really bottlenecked the system. The 8gb ram ultimately couldn't keep up with hungry chrome tabs and electron apps of the mid 2010's.
Yep the 8GB RAM is definitely a limit. I haven't done much coding on it yet tbh, for the light use I make of docker (php/apache/mariadb/vueJS) the RAM seems just ok. And it wouldnt run games that require more RAM anyway. (ps: for VSCode I did what was suggested online and turned off a bunch of extensions I don't really need).
In my case I had a left over 240 GB Samsung SSD from my last PC build. Replaced it with a 1TB nvme. So it was nice to also use a left over SSD. :)
Since then I read I could put a 1TB in it if I wanted - but that seems overkill as it's going to be more of a backup laptop.
What makes the experience so nice is in Ubuntu it would also show a nice popup for the media keys like volume up/down and brightness.
Even though that drive is slow and expensive by today's standards, I don't know if it ever really bottlenecked the system. The 8gb ram ultimately couldn't keep up with hungry chrome tabs and electron apps of the mid 2010's.