This is an artifact of V8's GC. Effectively, largeObject and smallObject are tracked together, as a unit. Splitting it out into two separate records increases a

This is an artifact of V8's GC. Effectively, largeObject and smallObject are tracked together, as a unit. Splitting it out into two separate records increases average memory usage. They keep saying they want to fix it eventually, but it's been this way for 10+ years at this point. You really do have to know the quirks of what you're targeting.