This will probably help:

    ;; Speed up magit status by removing some things
    (remove-hook 'magit-status-sections-hook 'magit-insert-tags-header)
    (remove-hook 'magit-status-sections-hook 'magit-insert-status-headers)
    (remove-hook 'magit-status-sections-hook 'magit-insert-unpushed-to-pushremote)
    (remove-hook 'magit-status-sections-hook 'magit-insert-unpulled-from-pushremote)
    (remove-hook 'magit-status-sections-hook 'magit-insert-unpulled-from-upstream)
    (remove-hook 'magit-status-sections-hook 'magit-insert-unpushed-to-upstream-or-recent)

It's because Magit is doing a lot more than just status. It executes multiple git commands to get all the information it wants to display.

As a sibling said, you can disable much of that.