memcached slow down site

Memcached is a service. By itself it cannot slow down your site. It’s the way your site operates with Memcached that either requires way more memory than available on shared hosting environment or it’s simply unoptimized to work with. It really depends on your plugins and how they interact with your database whether you will see your site faster or slower. You can keep it turned off and use the rest of the performance optimizations provided by the plugin. Each site is different and getting best results is what’s most important ??