Fifty timeline rows cost about 45 packmap shard reads after paint: each item's body is one loose-object read, and each sha lands in its own two-hex packmap shard. The shard promises are already memoized per context, so the reads are distinct shards, not repeats. Candidate fix: hydrate timeline card bodies from the items bodies corpus (a few shard reads for the whole window) instead of per-item object reads; weigh what the bodies corpus carries against what cards render, and the parity rule.