D-Filer

D-Filer program reads the file one line at a time to look for your search criteria and extracts any line which contains a matching string and appends to a file. Another option you can use is to break files up into many smaller files containing however many lines you choose, thus making said file easier to work with. Since D-Filer does not open the entire file into memory, you do not have to deal with a slow computer while handling your file, instead it reads one line at a time.