The introduction of the WebGL API for rendering 3D graphics within the browser has boosted the development of 3D Web applications. However, delivering 3D Web content without latency remains a challenging issue, not yet solved. In this context, we introduce a solution for fast progressive streaming and visualization of compressed 3D graphics on the Web. Our approach is based on two main features: (1) a dedicated progressive compression algorithm especially suited to Web-based environments. It produces a compact binary compressed format which allows very fast transmission as well as progressive decoding with levels of details. (2) a plugin-free solution for streaming, decoding and visualization by the Web browser, which relies on an optimized parallel JavaScript/WebGL implementation. Our system allows instantaneous interactive visualization by providing a good approximation of the 3D models in a few milliseconds even for huge data and low-bandwidth channels. Experiments and comparison with concurrent solutions for 3D web content delivery demonstrate its excellent results in terms of latency, adaptability and quality of user experience.