I have pushed an extension to the Pengines library that allows combining multiple events that require no input into a single event if they are generated within a specified time. That currently combines multiple output events, where SWISH configures this to wait for 10ms for a new event and collect them in batches of at most 100 events.
This greatly speeds up SWISH programs that use multiple write/format/… calls, reducing bandwidth requirements at the same time.
The patch also adds support for put_code/1 and put_char/1.