Results of the benchmark on my machine:

CURRENT CODE (3 runs)

getArgumentsAndReturnSizeFromDescriptor                thrpt   10  7841,639 ± 202,570  ops/s
getArgumentsAndReturnTypesFromDescriptor               thrpt   10  1444,529 ±  41,936  ops/s
getTypeFromDescriptor                                  thrpt   10  4586,855 ± 109,614  ops/s

getArgumentsAndReturnSizeFromDescriptor                thrpt   10  7884,111 ± 187,510  ops/s
getArgumentsAndReturnTypesFromDescriptor               thrpt   10  1448,835 ±  37,332  ops/s
getTypeFromDescriptor                                  thrpt   10  4578,097 ± 115,033  ops/s

getArgumentsAndReturnSizeFromDescriptor                thrpt   10  7868,005 ± 165,286  ops/s
getArgumentsAndReturnTypesFromDescriptor               thrpt   10  1453,131 ±  32,611  ops/s
getTypeFromDescriptor                                  thrpt   10  4537,437 ± 111,732  ops/s

NEW CODE (3 runs)

getArgumentsAndReturnSizeFromDescriptor                thrpt   10   7868,311 ± 205,813  ops/s
getArgumentsAndReturnTypesFromDescriptor               thrpt   10   1400,616 ±  47,122  ops/s
getTypeFromDescriptor                                  thrpt   10  10447,278 ± 285,315  ops/s

getArgumentsAndReturnSizeFromDescriptor                thrpt   10   7822,970 ± 180,999  ops/s
getArgumentsAndReturnTypesFromDescriptor               thrpt   10   1430,244 ±  39,596  ops/s
getTypeFromDescriptor                                  thrpt   10  10371,893 ± 308,044  ops/s

getArgumentsAndReturnSizeFromDescriptor                thrpt   10  7709,202 ± 168,070  ops/s
getArgumentsAndReturnTypesFromDescriptor               thrpt   10  1402,382 ±  34,459  ops/s
getTypeFromDescriptor                                  thrpt   10  8851,335 ± 259,663  ops/s