Caching & performance

The rule the whole plugin is built around: rendering never blocks on a remote API. The only exception is a feed's very first fetch, right after creation.

Stale-while-revalidate

• Fetched items are stored durably in the database (post meta on the feed, not transients — object caches may evict transients, which would break serving stale data).
• On render, whatever is cached is served immediately — fresh or stale. If it's past the feed's TTL (default 1 hour, per-feed setting), a one-off background refresh is scheduled so the next view is fresh.
• A 15-minute cron sweep also prefetches any feed past its TTL, so in practice visitors rarely even trigger the background path.

Failure behavior

• A failed fetch never clobbers cached items — the last good data keeps rendering, indefinitely if need be. The error is recorded and shown in the admin feed list (and to admins in empty.php if there's genuinely nothing cached).
• Consecutive failures back off exponentially (TTL × 2, ×4, …, capped at 6 hours) so a dead endpoint isn't hammered.
• A per-feed lock prevents fetch stampedes when cron and page loads overlap.

Image localization

Feed images are downloaded to wp-content/uploads/thewpfeeds/{feed_id}/ during fetch and served from your domain:

• LinkedIn image URLs are signed and expire within days — hotlinking them is broken by design; localization is the fix.
• Files are content-addressed per item, so unchanged posts skip re-downloading; images no longer referenced are pruned on each successful fetch; a feed's folder is deleted with the feed.
• If a download fails, templates transparently fall back to the remote URL — $item->image() always gives you the best available option.
• Nothing enters the WordPress media library — no attachment pollution.

Bonus effects: visitors' browsers never talk to LinkedIn/YouTube/Bluesky CDNs (privacy, GDPR posture), and images get your server's caching headers.

Tuning

• Per-feed TTL — feed setting, seconds (minimum 300).
• Item count — per feed, or per render via the block/thewpfeeds_render() args.
• The cron events are standard WP-Cron (thewpfeeds_refresh sweep + one-off refreshes). On low-traffic sites, wire WP-Cron to a real cron job as usual for punctual refreshes.