perf: comments-store deep clones via JSON.parse(JSON.stringify()), duplicating ~8 MB of strings

[tomcasaburi]

Problem

comments-store.ts calls utils.clone() (which uses JSON.parse(JSON.stringify())) three times per comment:

• Line 49: when saving to database
• Line 52: when adding to Zustand store
• Line 66: on comment updates

JSON.parse() creates new string instances for every property — V8 does not intern strings from JSON.parse. With ~26K comment objects on a typical board, this results in massive string duplication:

String	Copies	Wasted
ed25519	26,531	518 KB
1.0.0	26,528	518 KB
author	26,521	517 KB
business-and-finance.eth	16,180	562 KB
subplebbitAddress	16,569	517 KB
protocolVersion	15,652	427 KB
timestamp	16,563	388 KB
parentCid	15,487	362 KB
...and many more

Total: ~8 MB of duplicated strings in a single session.

Evidence

Measured via Chrome DevTools heap snapshots on 5chan (three snapshots: board page 1, catalog feed all 10 pages, reply section). The duplication counts are consistent across all three snapshots.

Existing pattern in the codebase

Two other stores already avoid this with an explicit comment:

replies-pages-store.ts (lines 96-97) and subplebbits-pages-store.ts (lines 98-99):

// don't clone the comment to save memory, comments remain a pointer to the page object
newComments[comment.cid] = comment

comments-store.ts should follow the same pattern.

Suggested fix

Remove utils.clone() calls in comments-store.ts and store comment references directly, matching replies-pages-store and subplebbits-pages-store. If cloning is required for some reason (e.g., preventing mutation), use shallow cloning ({ ...comment }) instead of deep cloning — this preserves shared string references.

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Co-authored with Claude Opus 4.6 (heap snapshot analysis and plebbit-js source investigation).