It used to, but the newer Docker for Mac uses xhyve which is more lightweight. It also by default runs a pretty stripped down version of Linux. The default VM size is 2Gb, but you can increase that if you need to.

I'm currently working on a project which involves a Docker replication of a production environment. The Docker Compose environment has 7 docker containers including Cassandra, Kafka and Flink plus some nodejs micro-services. This all runs happily in a 6Gb docker container leaving memory free for Eclipse, Atom, Outlook and a bunch of other applications on a 16Gb 2015 MacBook Pro. At no point have I felt that the machine is performing poorly due to memory exhaustion.

I'm comparing running on linux+docker vs running on linux. Virtualisation is present in both. If you've got the possibility to run the same app directly on OSX and you're not preparing for deployment on another system... why wouldn't you do that instead?

Docker for Mac uses the built-in Hypervisor.framework through xhyve. Still virtualizating Linux, though, so there's some overhead.