Well the problem is that the DSL uses strings, so any representation which keeps variable names as strings still needs storage and comparison, which currently only the fixed type does. Though c2dsl could instead use a unique integer for every string for variables.

The first value of each instruction would then always be one of a fixed set of opcodes, variables their IDs, and numbers left as-is (and we've invented machine code :)). Then (K, V) is always fixed-size and laid out predictably in memory, so the linear-search approach sounds reasonable.