I started to notice this in a big way at my last job which I started in 2013. We were a rails shop and by about 2016 I was noticing most new hires would have no idea how to write a SQL query.
probably why people think rails is slow. our integration partners and our customers are constantly amazed by how fast and efficient our system is. The secret is I know how to write a damn query. you can push a lot of logic that would otherwise be done in the api layer into a query. if done properly with the right indexes, its going to be WAY faster than pulling the data into the api server and doing clumsy data transformations there.
- relative speeds of programming languages (https://github.com/niklas-heer/speed-comparison)
- database indexing (https://stackoverflow.com/questions/1108/how-does-database-i...)
- numbers everyone should know (https://news.ycombinator.com/item?id=39658138)
And note that databases are generally written in C.
I wasn't trying to argue that ruby is slow (it objectively is). I was arguing that its slowness is irrelevant for most webapps because you should be offloading most of the load to your database with efficient queries.