This study investigates the performance differences between Rust compiled to WebAssembly and plain JavaScript, focusing on their efficiency in client-side web applications. By conducting a series of tests across various computational tasks, this research aims at providing insights into the potential advantages of using Rust and WebAssembly. The study evaluates metrics such as execution time, serialization overhead, and the impact of SIMD operations. I evaluated selected algorithms implemented in each technology on different input data sizes with varying numbers of repetitions. The results reveal that Rust implementations can achieve significant speedups, particularly when serialization overhead is minimized. The study also highlights the impact of JIT compilation on JavaScript’s performance, which improves with increased repetitions, while Rust’s performance remains stable. The findings suggest that for applications requiring consistent performance, WebAssembly and Rust should be the preferred choice. However, the study also notes the challenges of DOM API interactions, which require data to be passed back to JavaScript, potentially impacting performance.