The highly dynamic nature of Smalltalk provides a high degree of flexibility, but at the expense of performance. On the other hand, static system programming languages such as C are really fast, but less flexible and harder to use than Smalltalk. Our hypothesis is that by mixing the concepts of these two worlds in a single programming environment, we are able to have improved performance and a high level of flexibility at the same time. In this work we extend Pharo by adding a type system that provides the native data types present in C along with the dynamic object type. We extend Pharo compiler and virtual machine to use our type system by add custom bytecode instructions for dealing with native data. With our approach we obtain a performance improvement on average between two and five times faster for numerical computations using single precision floating point arithmetic in Smalltalk.