An analysis of JavaScript bundle sizes and performance impacts of session replay platforms reveals significant differences among vendors, with sizes ranging from Sentry's 36KB to Contentsquare's 553.4KB gzipped, affecting user experience. PostHog offers a 52.4KB bundle with lazy-loading features and transparent pricing, while Sentry has optimized its bundle to 36KB with detailed performance metrics provided. Fullstory adopts a static bundle approach at 58.8KB, prioritizing stability, and Pendo focuses on user onboarding with less performance transparency. Contentsquare's large bundle size impacts mobile performance, necessitating thorough testing for potential users. While performance trade-offs are generally acceptable for debugging, developers targeting mobile-heavy audiences or those with performance concerns should conduct specific tests using tools like PageSpeed Insights. Rollbar's new tool allows selective session replay recording to minimize performance overhead, aligning recorded data directly with debugging needs.