www.makemkv.com

Not sure if it is the lastest versions or if something else has changed, but encoding regular Blu-ray to MKV has started taking longer lately. A normal Blu-ray encode used to take my Windows 7 machine about 30 minutes or so to work...nothing has changed on my system except for updating to latest version of MakeMKV but for instance doing the Blu-ray for Turbo took almost 5 hours. I downloaded an older version of MakeMKV that I knew to be more stable on my system, but it seemed like it too was going to take forever. Do some Blu-rays just take this long to encode? Could something else have happened?

Could be the quality of the disc, or perhaps your drive is starting to fail and these are the symptoms of that.

Hard to tell unless you can narrow it down to when it happens precisely.

Adding to what crowfax said, I just ripped a 4-disk DVD set that took 45 minutes per disk. Same drive and computer had done several other disks, including BD and DVD, at 2 to 3 times that speed. The quality of the disk can have a serious impact on the reading speed.