hmm

[08:28:59 !502] 0
pr@pr:~$ time perl -e '"0~0000000000000000000000000000000000000000000~" =~ /^[0-2]~(([0-9A-F]{2})+|~)+$/'

real 0m0.006s
user 0m0.004s
sys 0m0.000s
[08:29:09 !503] 0
pr@pr:~$ time echo "0~0000000000000000000000000000000000000000000~" | egrep '^[0-2]~(([0-9A-F]{2})+|~)+$'

real 0m0.004s
user 0m0.000s
sys 0m0.004s
[08:29:26 !504] 1
pr@pr:~$