Aspects of the UPSC syllabus that require extensive memorization include current affairs, static general knowledge, and core subjects like polity, geography, and history. Memorization is essential for retaining information about various laws, constitutional articles, significant dates, and historical figures essential to understanding the civil service framework. Additionally, familiarity with statistical data in economics and geography plays a role. Building mnemonic devices and revisiting topics regularly enhances retention and recall capabilities for the exam.