I agree with BrowserUK that loading such a huge file into memory even before you start reading the first line is a no go. You really want to iterate line by line over the file to reduce the memory used. Having said that, it is unlikely you will be able to fit 5 million megabytes into a hash.

On your CPU usage question, how many CPUs/cores do you have?

In reply to Re: Reduce CPU utilization time in reading file using perl by Laurent_R
in thread Reduce CPU utilization time in reading file using perl by madtoperl

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