Fix Admin-Ajax CPU Spikes and optimize the website

Our WordPress site is buckling whenever wp-admin/admin-ajax.php fires during routine back-end work. CPU load jumps from its normal sub-20 % to a sustained 100 %, bringing everything else to a crawl. I’m... (Budget: $10 - $30 USD, Jobs: AJAX, JavaScript, Nginx, Performance Tuning, PHP, Redis, Website Optimization, WordPress)