Turpentine is a Magento extension to improve Magento's compatibility with Varnish, a very-fast caching reverse-proxy. By default, Varnish doesn't cache requests with cookies and Magento sends the frontend cookie with every request causing a (near) zero hit-rate for Varnish's cache. Turpentine provides Varnish configuration files (VCLs) to work with Magento and modifies Magento's behaviour to significantly improve the cache hit rate.
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