Render webpage to hard disk instead to RAM.
Actually most of the users want's exactly the opposite.
The Chr engine does already an high IO traffic, and many people (me included) are using a RAMdisk for the cache.
The RAM is cheap nowadays, the HDD traffic makes the experience deadly slow, while the high traffic over a way faster SSD contribute to its wearing.
In both cases also the high traffic over the storage can make a small FS error way worse.
The compression can be already used on a ramdisk (just format it as NTFS and compress it), the zram idea could be a good one, but (I guess) it requires some major engine changes, something that is not feasible nowadays because the limited Vivaldi resources, and the constant engine updates.