@info2x wrote: "tried using Photo Mechanic and am getting similar speeds."
If importing via Explorer is fast, but LrC and Photo Mechanic are slow, then @JohanElzenga comment re previews is worth following up.
Personally, when using faster SD and CF Express cards I find it quicker to copy files from the card to disk using macOS Finder, then use LrC's 'Add'.
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