I've done CPU laden tasks many times in Node. The key is how you break up the heavy task into pieces that can be distributed more evenly on the event loop instead of blocking it. For example processing a huge data stream is typically done by breaking it into chunks where each chunk can be processed in a few ms, rather than doing one giant blocking operation on the entire stream.

Done properly this also leads to a low memory process that will grab data from an incoming socket stream, transform it, then push that data back out through an outgoing socket stream, only ever keeping a few MB of the stream in working memory at a time. Slap a cluster of these streaming processes together running on a single box to utilize all CPU cores and you can easily push many Mbps of IO through your server quickly and efficiently.

Additionally even if you do have a heavy blocking system IO operation that you can't break up very well you can increase `UV_THREADPOOL_SIZE` when needed to reduce the impact of the blocking.