High Sierra takes long time to install +16 hours

Hello, first of all, I want to say thank you for replay and second of all, Yes I do have a ssd in it, true. But If I put back in a hdd, am I going to expect slow and laggy installation again or do I really need to replace the hdd cable? Because today I installed windows 10 on it, and installation went smoothly and fast, it took 10 minutes for win10 to install on my macbook and overall it's smooth, so is it really the problem with the hdd cable?

If you take the time and look through the questions for your system you'll find many others telling us the same.

I've fixed 100's yes that many! All of them sang after replacing the cable as I outlined and re-doing the format & OS install. If you want Windows then stick with it! If you want macOS you know what's needed.

While Windows appears to work its not going to be stable.

Well I do have a windows pc, so no need to have it on my macbook. But alright, if you say so. I'll try to update you in a few weeks. Thank you!

I got my hdd MacBook pro 2012 cable for my early 2011 and guess what, everything is still the same, laggy pre-instalation, laggy mouse pointer..

Yep that makes total sense as the older cable is only SATA II and you likely damaged it or got damaged.

Lets start again you need the BETTER cable MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable This is the 2012 version which is the BETTER Cable. Second you need to place a strip of tape on the uppercase where the cable crosses as outlined in Your Hard Drive Cable Is A Ticking Time Bomb and lastly you need to rolled the bends not crease it as that damages it! I use a BIC pen ink tube as a form to roll the bends so they have a nice radius.

OK, now that the hardware is fixed you still need to reformat your drive and install a fresh copy of your macOS.

We've collectively done tons of these, I can tell you I for one have done at least 250 systems like yours with the exact same symptoms! Everyone was working and screaming in speed!