: We are building an infrastructure for the platform-independent distribution and execution of high-performance mobile code as a future Internet technology to complement and perhaps eventually succeed Java. Key to our architecture is a representation for mobile code that is based on adaptive compression of syntax trees. Not only is this representation more than twice as dense as Java byte-codes, but it also encodes semantic information on a much higher level. Unlike linear abstract-machine representations such as p-code and Java byte-codes, our format preserves structural information that is directly beneficial for advanced code optimizations. Our architecture provides fast on-the-fly native-code generation at load time. To increase performance further, a low-priority compilation thread continually re-optimizes the already executing software base in the background. Since this is strictly a re-compilation of already existing code, and since it occurs completely in the backgro...