Since they started charging for checked bags, now everyone tries to carry on as much as they can which results in slow boarding and getting off.

They should be charging for overhead bin use and make checked bags be free (along with small bags under the seat in front of you). This way most people would go back to checking bags and only the business people or people willing to pay would carry-on.

With planes being so overbooked these days I often carry my bag through security (which slows that down!) but then gate check it for free (so the airline is now losing the revenue).