Doesn't matter if SQLite is now viable with rails, no legacy rails app is using it and it's not like you're going to wake up one morning and migrate your production db from postgres, mysql, sql server or oracle just because you felt like it.
In theory the language is slow, in practice it doesn't really matter because the db is much slower unless you're github or twitter and you really need to scale.
When you choose ruby, you trade faster dev time for slower runtime. I am OK with this trade-off 99% of the time. My dev time costs way more than a couple ms lost on my production server.
> When you choose ruby, you trade faster dev time for slower runtime.
Ruby is a beautiful language, but that does not translate to efficient use of dev time. Ruby is not a language that you can quickly write usable code in. Some other languages are clearly more productive. You can create works of art, though, which is still pretty appealing. Ruby does have a place in this world.
It was, again, DHH/Rails that used to make the claim about developer time — premised on Rails eliminating all the so-called "situps" that other frameworks imposed on developers. It is very true that when you eliminate a bunch of steps you can move a lot faster. But:
1. Everyone and their bother have created Rails clones in other languages that also eliminate the same "situps", negating any uniqueness Rails once offered on that front.
2. It turns out those "situps", while a dog in early development, actually speed development up down the road. If you are churning out a prototype to demonstrate an idea that will be thrown away after, its a pretty good tradeoff to ignore what you can, but things become far less clear cut when a program finds longevity.
In theory the language is slow, in practice it doesn't really matter because the db is much slower unless you're github or twitter and you really need to scale.
When you choose ruby, you trade faster dev time for slower runtime. I am OK with this trade-off 99% of the time. My dev time costs way more than a couple ms lost on my production server.