Fun bash fact of the day: keep your variable names short - you can get a noticeable performance improvement! (don't actually do that, if you care about this kind of performance in bash pick a different language -.-)

output

Testing bash
It took an average of 8.765s to assign to the variable v
It took an average of 8.884s to assign to the variable vvvvv
It took an average of 8.973s to assign to the variable vvvvvvvvvv
It took an average of 9.040s to assign to the variable vvvvvvvvvvvvvvvvvvvv

variable_name_test.zsh

#!/usr/bin/env zsh

shell=${1:-bash}

echo "Testing $shell"

zmodload zsh/datetime

for name in v vvvvv vvvvvvvvvv vvvvvvvvvvvvvvvvvvvv; do
  time=0
  for t in {1..5}; do
    start=$EPOCHREALTIME
    $shell -c "for ((i = 0; i < 1000000; i++)); do $name='x'; done"
    end=$EPOCHREALTIME
    ((time += end-start))
  done
  printf "It took an average of %.3fs to assign to the variable %s\n" \
         $((time / 5)) $name
done