Best way to work with JSON data

So I need to import 3 json files, they range from 10MB to 40MB in size. Each of them has data that coincides with data in the others. What is the best way to import the data and use it? Right now I just have like

$json1 = get-content .file.txt | convertfrom-json 

Then i just use $json1.result.field that I need. Would it be easier/faster to use custom objects or just leave it as it?