A source code file can be compiled to generate bytecode. During compilation, a first use of a local variable within a set of instructions of the source code can be detected. A local variable usage list can be examined for at least one inactive local variable in use by the set of instructions. An existence of an acceptable type pairing between a type descriptor corresponding to a local variable and a type descriptor of the local variable may be determined. When the acceptable type pairing exists, an index of the local variable array corresponding to the determined acceptable type pairing for the local variable can be reused. Otherwise, a new index can be assigned for the local variable. Compiling bytecode in this manner avoids extraneous class loads that would otherwise occur during a verification phase of the bytecode, which has still been optimized to reuse local variable slots.