Add benchmark for hash-fetch

Calculating -------------------------------------
 fetch with no block     66979 i/100ms
  fetch with a block    138257 i/100ms
 brackets with an ||    145792 i/100ms
-------------------------------------------------
 fetch with no block  1255521.2 (±5.2%) i/s -    6296026 in   5.028856s
  fetch with a block  6402972.5 (±8.1%) i/s -   31799110 in   5.002554s
 brackets with an ||  8536511.4 (±8.1%) i/s -   42425472 in   5.005831s