Get all lines containing a string in a huge text file - as fast as possible?

Question

In Powershell, how to read and get as fast as possible the last line (or all the lines) which contains a specific string in a huge text file (about 200000 lines / 30 MBytes) ?

Answer 1

I wanted to extract the lines that contained failed and also write this lines to a new file, I will add the full command for this

get-content log.txt -ReadCount 1000 |
>>  foreach { $_ -match "failed" } | Out-File C:\failes.txt