Looking to improve searches across large ( 7-10 GB files )

I have a need to search for many ( thousands) of dns within a large ( 7-10 GB) ldif file and print out the entries after it . I am mostly familiar with shell/python so tried to use awk for this and it works but it is a bit slow. I use a counter when it finds a matching line - print everything under there and reset back to 0 if the line doesn't start with dn. I can't use grep -A because each entry can contain different number of lines to be printed . I don't have the means to import this into another ldap/db with indexing..just looking for something quick that I can use for now . if anyone knows any Linux-fu that can help please let me know! sorry I meant like the dn: pattern in an ldif file. For clarity - here is what I want I have a file with - dn: pattern1 phone: xxxx email: yyyy dn: pattern2 phone: xxxx email: yyy I have the dn: pattern that needs to be searched and the lines below that to be printed - till it reaches the next line with dn: . There is one empty line between entries. This is my code so far awk -v dn="$dn" ' BEGIN { counter = 0 } { if ($0 ~ /^dn: /) { if ($0 == dn) { counter = 1 } else if (counter) { exit } } if (counter) { print } } '