Selected regions of native instructions translated in a DBT environment from non-native instructions are compressed based on the independent compression of different fields of selected instructions using compression tables to reduce a length of selected fields. The regions of compressed instructions are stored and de-compressed into the native instructions during subsequent execution using de-compression tables. Specifically, for native instructions of a selected region, selected types of opcodes and/or operands may be compressed independently. The types may be selected by profiling the opcodes using benchmark programs and creating an opcode conversion table prior to compression, and scanning of the operands and creating an operand conversion table during compression of the opcodes.