Cache plugin for Osclass Classifieds generates static html files from your dynamic Osclass website. Basically without plugin when any page is rendered, php and mysql are used and osclass executes all required functions and queries to render website. This require server RAM and CPU and decrease performance of Osclass (more plugins and listings are active, slower performance is). If many users come to a website, server uses lots of RAM and CPU so page is rendered so slowly and it leads to bad performance and user experience. To avoid this scenario, it is required to use a cache system not to render page again and again, but just once and then reuse html output for other visitors.
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