Cassandra and HSQLDB are written in Java for example which usually suffer from much larger GC collections/pauses (though you can read a book or two on the subject and tune it). So is Neo4j, a graph database. Or Datomic in Clojure (which runs on the JVM). Then there's Mnesia written in Erlang. A time series database, or a graph database, is quite different from a more general purpose database like Postgres/MySQL and means you need to consider different things.
GC isn't necessarily an issue for high throughput (read or write). A lot of it depends on how much pressure you're putting on the GC (this is true for any type of application). Being aware of how your chosen language's GC behaves paired with the (typical) usage/behaviour of your code is probably the more important thing to consider. Just because something is written in a language without a GC doesn't automatically make it performant either.
Here is our measurement dashboard for a functional test cluster: http://dash.etcd.io/dashboard/db/functional-tests?from=now-2...
I am a big fan of golang for some workload but the GC will kill performance in a database, wouldn't?
I am not being a brat I am seriously wondering how much GC affect the overall performance.