Skip Loading Translations on English Sites

// 'frontend' skips translations on public pages only. 'everywhere' also skips them in wp-admin.
$wpide_skip_translations_on = 'frontend';

// Text domains that still load their translations, for example 'default' (WordPress itself) or 'woocommerce'.
$wpide_keep_text_domains = array();

$wpide_skip_translation = function ( $domain ) use ( $wpide_skip_translations_on, $wpide_keep_text_domains ) {
    if ( in_array( $domain, $wpide_keep_text_domains, true ) ) {
        return false;
    }

    if ( 'everywhere' === $wpide_skip_translations_on ) {
        return true;
    }

    if ( is_admin() || wp_doing_ajax() || wp_doing_cron() || ( defined( 'WP_CLI' ) && WP_CLI ) || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
        return false;
    }

    if ( isset( $GLOBALS['pagenow'] ) && 'wp-login.php' === $GLOBALS['pagenow'] ) {
        return false;
    }

    // REST requests are not flagged yet when the first translations load, so check the address too.
    $uri = isset( $_SERVER['REQUEST_URI'] ) ? (string) wp_unslash( $_SERVER['REQUEST_URI'] ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput

    return ! isset( $_GET['rest_route'] ) && false === strpos( $uri, '/' . rest_get_url_prefix() . '/' ); // phpcs:ignore WordPress.Security.NonceVerification
};

// PHP translation files (.mo and .l10n.php).
add_filter( 'override_load_textdomain', function ( $override, $domain ) use ( $wpide_skip_translation ) {
    return $override || $wpide_skip_translation( $domain );
}, 10, 2 );

// JavaScript translation files (.json).
add_filter( 'pre_load_script_translations', function ( $translations, $file, $handle, $domain ) use ( $wpide_skip_translation ) {
    return ( null === $translations && $wpide_skip_translation( $domain ) ) ? false : $translations;
}, 10, 4 );