Depending on what value your looking for, you might be able to do it with this scrip https://github.com/kenmarz/harparse/blob/master/harparse.py

python harparse.py --help

This script helps parse json formatted HAR files

options:

--url (ie: --url=favicon) Search and return any url with a match for the given value --gt (ie: --gt=1000) Returns any url response taking longer in milliseconds than the given value --tt Returns only the url timing breakdown (no headers) --cookies Must be passed with --url to returns cookies for the matching url/value

example: python example.com.har --url='favicon' --gt=1000

The example returns the headers and timing for any url matching favicon whose total time is greater than 1000ms