I am facing a severe performance issue on a WordPress site where the Case Study listing page (/case-study/) takes 60+ seconds to load, while individual Case Study detail pages load normally (~500 ms).

I have investigated this using Query Monitor, and the results are confusing because database performance looks fine.

Environment

• WordPress (latest)

• Custom theme + child theme

• Plugin heavily involved: enovathemes-addons

• Page builder based layout

• PHP with OPcache enabled

• APCu installed and APCu Object Cache plugin enabled

Observed behavior

• /case-study/ (listing page): ~63 seconds page generation time

• /case-study/single-post/: ~512 ms

• Frontend network requests load normally once the page responds

Query Monitor results

• Page Generation Time: 63.13s

• Database Queries: 223 queries

• Total DB time: ~0.8s

• Peak Memory Usage: ~32 MB

• HTTP API calls: None

• Object Cache hit rate: ~93%

• Persistent object cache: Enabled (APCu)

Despite enabling APCu, there is no noticeable performance improvement.

Errors / Warnings

Query Monitor shows repeated PHP warnings during page load:

Warning: Attempt to read property "guid" on null
wp-content/plugins/enovathemes-addons/shortcodes/shortcodes.php

This warning appears multiple times while rendering the Case Study listing page.Relevant code snippet (shortcode function)

The plugin uses shortcodes to render elements like logos. One example:

$logo = get_post($logo);
$logo_src = $logo->guid;

get_post() sometimes returns null, but the code accesses $logo->guid without validation.
There are also calls like:

file_get_contents($logo->guid);