If you're able to produce high quality videos using PD15, then nothing is wrong and there's no reason to uninstall/reinstall it. Although it might not seem like it, there are often too many subtle variables to make a direct comparison between Handbrake and PD.
For example, the output profile you choose for PD can be the sole reason that producing a 6GB HD video takes 3 hours or 3 minutes, even with the exact same timeline edits.
If you'd like to see if other people get similar or very different results, you'd need to share your specific project which includes all your source clips. To do that, use Pack Project Materials... under the File menu and save everything to a cloud folder on Google Drive or OneDrvie and paste a shareable link here.
If you're not comfortable doing that, upload a short sample vid from your Hero 7 so we can at least see what the best output profile would be for your projects.
Please see the
Share a file publicly section in this Google
FAQ page, or check this OneDrive support
page if you need more info.
YouTube/optodata
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