I use very little of my Raspberry Pi 2B's CPU, but I frequently need more memory. In order to free up memory on my Pi running Ubuntu MATE, I set up Zram by installing zram-config. I was pleasantly surprised at the difference it made.
Now, after installing Raspbian Stretch for the first time I decided to set up Zram on it. I followed this guide to configure Zram, and everything went as it should, on boot-up four Zram blocks are set up. There is also now 1 GB of swap space instead of 100 MiB. There does not seem to be any difference in behaviour however.
On Ubuntu MATE
htop shows a lot of swapping (into the Zram, there is no swapfile) but on Raspbian there is no swapping happening at all. There used to be a little bit of swap to the swapfile, but now there is nothing at all. (see image below).
EDIT: My Zram is actually active, but the swap is still very low. There is generally just a little bit more swap than there was originally without Zram. My swappiness is set to 60, the same as on my Ubuntu. Maybe it just works a little differently on Raspbian.