It turned out that ZoneAllocator is the largest memory consumer when a renderer process hits its peak memory. ZoneAllocator can consume 10 - 30% of the peak memory [1]. The current ZoneAllocator is optimized for performance and doesn't free any memory until V8 finishes parsing.

We need to find a way to reduce the memory usage at least on low-RAM devices.

https://docs.google.com/spreadsheets/d/1Cm4GKQDKxXbvo7nEA-PwXpidmdBvW7jGsP1J4D2LM3E/edit?pref=2&pli=1#gid=169265592