When I started using MakeMKV over a year ago, I too wondered why my drive would only rip at 2x. After doing some research, my particular drive couldn't be "unlocked" to rip faster. I think the forum over at MakeMKV has quite a bit of information on if your drive is riplocked and how to rid it of that 'feature' if it even can.
Honestly, to me, I don't even worry about it anymore. I put in a Bluray and walk away for about 45 minutes while it rips.