I've heard ZRAM mentioned before and I've just spent 5 minutes reading articles on it... Which is about the maximum I have time for these days when it comes to

I've heard ZRAM mentioned before and I've just spent 5 minutes reading articles on it... Which is about the maximum I have time for these days when it comes to esoteric linux internals. What's the downside? Does it use much CPU? If I have enough RAM already, should I still enable it? One article says it can be mapped to /tmp to reduce i/o. Is that a good idea? This article is light on all of these kind of details.