Comment by array_key_first

You don't need to go balls to the wall and allocate 100% upfront. The typical split we see is either "allocate all the things" or "allocate every object, even if it's 16 bytes and lives for 100 microseconds".

Most programs have logical splits where you can allocate. A spreadsheet might allocate every page when it's created, or a browser every tab. Or a game every level. We can even go a level deeper if we want. Maybe we allocate every sheet in a spreadsheet, but in 128x128 cell chunks. Like Minecraft.