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Problem:
The client reported high database query usage by the WPML plugin, causing slow performance in their online store, especially under high traffic. Despite trying various caching plugins and optimizations, the issue persisted.
Solution:
We identified that the performance impact was primarily from the TemplateMela Core plugin, particularly the TemplateMelaCore_Elementor_Product_Category::render() function used in the main menu. We recommended disabling this plugin or replacing it with a more optimized solution for the main menu to reduce the number of queries and improve performance.

Further, we provided code improvements for caching:

if (\Elementor\Plugin::$instance->editor->is_edit_mode() || \Elementor\Plugin::$instance->preview->is_preview_mode()) {

This code ensures that caching does not interfere with live editing in Elementor.

We also suggested refining cache invalidation to be less aggressive and only clear the cache for relevant changes:

add_action('created_term', 'tm_clear_menu_cache_on_product_cat', 10, 3);<br />add_action('edited_term', 'tm_clear_menu_cache_on_product_cat', 10, 3);<br />add_action('delete_term', 'tm_clear_menu_cache_on_product_cat', 10, 3);<br />function tm_clear_menu_cache_on_product_cat($term_id, $tt_id, $taxonomy) {<br />    if ($taxonomy !== 'product_cat') {<br />        return;<br />    }<br />    // ... clear cache<br />}

Additionally, we recommended including a hash of widget settings in the cache key to make caching more effective:

$settings_hash = md5(serialize($widget->get_settings_for_display()));<br />$cache_key = 'tm_menu_' . $widget_id . '_' . $lang . '_' . $settings_hash;

If these solutions do not fully resolve the issue or if they become outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If the problem persists, please open a new support ticket at WPML support forum.