$ time perl large_file_regex_search.pl
100000: 1 s
200000: 2 s
300000: 3 s
400000: 4 s
500000: 5 s
600000: 5 s
700000: 6 s
800000: 7 s
900000: 8 s
1000000: 10 s
1100000: 15 s
1200000: 18 s
1300000: 20 s
1400000: 23 s
1500000: 25 s
1600000: 29 s
1700000: 35 s
1800000: 42 s
1900000: 47 s
2000000: 53 s
2100000: 60 s
2200000: 66 s
2300000: 71 s
2400000: 75 s
2500000: 81 s
2600000: 87 s
2700000: 92 s
2800000: 98 s
2900000: 103 s
3000000: 107 s
3100000: 113 s
3200000: 119 s
3300000: 124 s
3400000: 129 s
3500000: 135 s
3600000: 142 s
3700000: 151 s
3800000: 158 s
3900000: 166 s
4000000: 173 s
4100000: 181 s
{
  aNumber => 4140847,
  CorporateRecord => 149943,
  newRec2 => 783275,
  null => 4140847,
  oldRec => 987898,
}
real    3m5.660s
user    1m6.390s
sys     0m16.875s

$ $ ls -al FI*
-rw-r--r-- 1 Roboticus None       1261 May 30 12:12 FILES.ddl.sql
-rw-r--r-- 1 Roboticus None 3248770142 Jul 21 08:47 FILESRCH.1
-rw-r--r-- 1 Roboticus None  116430098 Jul 21 08:47 FILESRCH.2
-rw-r--r-- 1 Roboticus None 3248770142 Jul 21 08:47 FILESRCH.3
-rw-r--r-- 1 Roboticus None  769188466 Jul 21 08:47 FILESRCH.4
-rw-r--r-- 1 Roboticus None          0 Jul 21 08:44 FILESRCH.5
-rw-r--r-- 1 Roboticus None  613214364 Jul 21 08:47 FILESRCH.6