The Static Assembler is a Pega tool used to address rules assembly issues specifically when the server is managing a large number of rules caches. By pre-assembling rules into a static content, the Static Assembler helps in improving performance in situations where cache management becomes complex due to the volume of rules. It creates a set of static files that represents the assembled rules, which can reduce the overhead on the server during rule assembly and cache management. Reference: Pega official documentation on performance tools and best practices.