Windows 10: BitLocker Encryption process VERY Slow on Win10

Discus and support BitLocker Encryption process VERY Slow on Win10 in AntiVirus, Firewalls and System Security to solve the problem; I just installed Win10 Pro and I love it. When I enabled BitLocker, I selected to encrypt the Entire drive instead of the Used Space because I just... Discussion in 'AntiVirus, Firewalls and System Security' started by win10freak, Jan 2, 2016.

  1. BitLocker Encryption process VERY Slow on Win10

    I just installed Win10 Pro and I love it.
    When I enabled BitLocker, I selected to encrypt the Entire drive instead of the Used Space because I just feel I am safer with encrypting the entire drive. And my drive is not new. It had Win7 running before.

    So I did a clean install of Win10 pro with BitLocker enabled to set to encrypt the ENTIRE drive.
    The encryption process took 7 hours to complete on a 300GB internal disk drive

    When I had Win7 (and even Win8.1), it did not take that long to encrypt and I have the same exact internal drive.
    In Win7, the whole process took 1 hour. And with Win8.1 took a bit more time, but not 7 hours...

    Why is entire disk encryption takes this long on Win10?

    And also, I do not have a whole lot of programs installed. I have like 6 programs installed and there not that huge in size.


    win10freak, Jan 2, 2016

  2. Bitlocker encryption takes long titme on Windows 10

    Original title: Encryption of hard drive

    Good morning

    I recently upgraded to Windows 10 professional, and have been trying to encrypt my hard drive using Bitlocker.

    The system has been encrypting for several days now, but still has only managed to encrypt 0.7% of the hard drive.

    Is there something blocking or slowing this down, as it seems very slow to me.

    The hard drive does have around 91G on it but even so.

    Can anyone help me with this?


    Dave Roberts
    DavidRoberts7016, Jan 2, 2016
  3. Restore system image from a bitlocker encrypted external USB drive (Windows 10)


    I'm going to encrypt my C: drive with Bitlocker. I also want to save a complete system image on an external USB drive. Which shall be encrypted with Bitlocker as well.

    My question:

    Is is possible to restore a complete system image from a Bitlocker encrypted external USB drive?

    My assumed experience:

    My internal drive brakes and I replace it with a brand new drive. I connect the encrypted external USB drive (with the system image on it) at my laptop. I boot from a Win10 USB-Stick and go to the recovery/restore options. There I'm able to select the external
    USB drive and have to enter my PIN/password to decrypt the drive. Than the restore process starts. After a reboot I'm back at my old environment.

    Is that the case that will happen?
    zerpixelung, Jan 2, 2016
  4. ppilihp Win User

    BitLocker Encryption process VERY Slow on Win10

    I don't know why this is, but it is ULTRA SLOW indeed. I recently bought a WD Blue 4 TB drive and Bitlocker is already encrypting it for more than 50 hours and is still at only at 68.3%.

    According to the Windows Taskmanager the Bitlocker process is using the drive at 100%, constantly reading off and writing on it at 7-15 MB/s. I don't know about the mechanics of a harddrive, but running at 100% for 75 hours (>3 days!) isn't going to improve its health.

    I chose the offered new encryption XTS-AES.

    In the past, encrypting a whole drive always took some time, but even with drives as big as 3 TB it never took more than 24 hours.

    I guess it is some kind of bug and i hope that Microsoft will fix it.

    ppilihp, Jan 7, 2016
  5. DMGrier Win User
    If I may ask are you on a HDD or a SSD? I know my 250 GB SSD took about 2 hours to encrypt with the XTS-AES 256 Bit encryption for the whole drive. I know I have not been pleased with Windows 10 performance on the HDD in my wife's computer.

    Now I think Microsoft has just finally fixed many of the security problems with Bitlocker as I have always read that Bitlocker is a good encryption but has loop holes. At my work with our slow role out of Windows 10 we have started to use Bitlocker but I do know on our Windows 7 machines when using TrueCrypt in the past and DiskEncryptor to do a full drive 256 Bit encryption on a 500GB drive typically takes around 7-9 hours depending on the generation of Intel CPU as many of the machines that are 2nd Gen i3 still running around.

    I do know what your saying that Bitlocker in the past did encrypt faster but I always questioned on how that was when I have used so many other encryption tools that took so much longer. Personally I feel safer to see Bitlocker taking around the same time that every other software I have used in the past.
    DMGrier, Jan 8, 2016
  6. ppilihp Win User
    Did you address me or the OP?

    My drive is an internal SATA3 HDD. It is still encrypting btw *Biggrin Right now it is at 92%. So my ETA is in a couple of hours or 3 1/2 days total. Granted I used the PC and the disk a couple of times today, which seems to interrupt the encryption process. Btw. copying files to and from the disk works with 110 - 150 MB/s throughput (avg. 120-130 MB/s). That's what I usually get from SATA3 connections.

    For purposes of comparison I started to encrypt a 1 TB WD Blue SATA3 HDD in an external USB 3 case and that went considerably quicker. The Bitlocker process wrote and read at around 50 MB/s and finished within a couple of hours today.

    Since you mentioned it: Encrypting SSDs under Win 10 wasn't without its issues for me, either. While you could easily use Win 8/8.1 while encrypting a SSD, the encryption process under Windows 10 sucked all the life out of the two PCs I encrypted (both powerful machines). The advantage may be, that the encryption finishes fast, but it still sucks if you actually wanted to work in the meantime.
    ppilihp, Jan 9, 2016
  7. ARC1020 Win User
    Yeah, if you opt to do the whole disc in one go then it can take a while. I found for SATA drives, the time taken to encrypt using XTS-AES 128, at opposite ends of the spectrum, were approximately as follows:

    1TB HDD, SATA II motherboard with non AES-NI supported Processor = Approx. 28 Hours

    1TB SSD, SATA III motherboard with AES-NI supported Processor = Approx. 12.5 Hours
    ARC1020, Jan 16, 2016
  8. PantherDD Win User

    BitLocker Encryption process VERY Slow on Win10

    To get a 5x speed boost on encrypting your full drive in Windows 10:
    1. Enable Bitlocker in the running OS, but pause the encryption once it's in progress
    2. Create a recovery disk, boot it up, go to command line
    3. Resume encryption of the drive using "manage-bde -resume" while in the recovery environment
    (4. Pause again at 99% and go back to the running OS and finish it from there...? This is probably unnecessary, but this is what I did.)


    I just tried to encrypt my 2TB external HDD on the latest Windows 10 Pro using Bitlocker (entire drive, compatible mode), and since I only got to 3% within ~2 hours, I started looking into what was going on. I checked on Task Manager's Performance tab, and while CPU and memory was idling, disk usage on the affected drive was at 100% constantly. However, at the same time, it reported 10 MB/s read and also 10 MB/s write, which was very slow compared to how this drive performs when I read / write files myself. This is when I started searching the internet and found this thread.

    First I wanted to obtain a Windows 8.1 Recovery Disk, to try to boot it up and encrypt the drive from the command line tool "manage-bde", hoping that it would be a lot faster as reported here. However, I wasn't able to find an ISO for that recovery disk, so I gave up on that. But as a last effort, I decided to try the same with the Windows 10 Recovery Disk that I could simply create from my running OS. And the trick worked!

    Windows 10 Pro (same machine, same drive, same everything!), Running OS vs. Recovery Disk
    (I will just post the results in "percent per hour", as it shows the speedup just fine, but if you'd like, you can calculate MB/s.)

    === Encryption phase 1 - Running OS ===
    20:13 - 0.0%
    00:01 - 5.9% --> 1.553% per hour

    === Encryption phase 2 - Recovery Disk ===
    00:08 - 5.9%
    00:39 - 11.0% --> 9.871% per hour
    02:07 - 25.3% --> 9.750% per hour
    04:44 - 50.0% --> 9.439% per hour
    11:41 - 99.2% --> 7.079% per hour

    === Encryption phase 3 - Running OS ===
    12:10 - 99.2%
    12:41 - 100.0% --> 1.548% per hour

    === Results ===
    Running OS: average 1.55% per hour; estimated total 64.5 hours
    Recovery Disk: average 8.08% per hour; estimated total 12.4 hours
    SPEED UP: ~5x

    My guess is that Windows 10 is throttling the encryption process to a "safe speed" for some reason, probably to keep the system usable while it's working. You can see that the processing speed is approximately the same at the start (~0%) and at the end (~100%) when the OS is running, whereas it gradually slows as we get to the slower parts of the disk while encrypting in the recovery environment. So basically the disk IO is really maxed out in the recovery environment, while the bottleneck is somewhere else in the running OS.
    PantherDD, Jun 15, 2016
  9. thedoc46 Win User
    I've had a 4TB USB3.0 ext drive encrypting now using full disk and the older AES 128, running in recovery mode for 48hrs and its done 27%. Wish i never bothered now.. Can kill it, you can either pause or resume and that's your lot !
    thedoc46, Dec 7, 2016
  10. PantherDD Win User
    That's strange... So you booted from a recovery CD / pendrive, issued "manage-bde -resume" from the command line, and it's still as slow as from within the running OS?
    If you want to go back to the running OS, just issue a "manage-bde -pause" and reboot.
    PantherDD, Dec 7, 2016
  11. thedoc46 Win User
    Correct. doing it from outside the O/S seems to be around the same speed, as in painfully slow !!!! i've just reverted to continuing in Win10. My other option that may or may not work is fire up a Win7 Ultimate laptop, and perhaps continue the encryption from there, if it would let me? i've not tried. Also don't want to render a new ext 4TB drive useless.
    thedoc46, Dec 7, 2016
  12. PantherDD Win User
    Well, if it's new and there's no data on it yet, you've got nothing to lose. Feel free to try Windows 7, my guess is that it would work just fine, but if it doesn't, you can just reformat / repartition the drive and start over.

    Actually, if the drive is new and empty, why don't you encrypt "data only"? That would be done in seconds.
    PantherDD, Dec 7, 2016
  13. thedoc46 Win User

    BitLocker Encryption process VERY Slow on Win10

    kinda 4 days in now, and worried if i try and restart the encryption in Win7, something bad may happen to the new drive..

    Also the 'encrypt data only' option, i was unsure about... if i took that option, then everytime i copy data, does it take ages to copy over as it encrypts? its not very clear.
    thedoc46, Dec 7, 2016
  14. PantherDD Win User
    "something bad may happen to the new drive" -- The encryption is purely a software thing, there is no chance for physical damage, no matter how much you screw up. *Smile (Well, you could overheat the drive or wear it down with the amount of disk activity the encryption causes, but that would be independent of whether you switch to Win7 or not.)

    "everytime i copy data, does it take ages to copy over as it encrypts?" -- Writing to or reading from an encrypted drive always has the overhead of encrypting or decrypting the data. (In other words, it will have to encrypt the new data as you copy it onto the drive even if you used the "encrypt entire drive " option.) However, if you have a good enough CPU, it won't slow your system down. And if you don't, well, it's going to be painful no matter whether you encrypted the entire drive or used disk space only.
    PantherDD, Dec 7, 2016
  15. thedoc46 Win User
    Thanks, guess i'm learning stuff about Bitlocker ! *Smile I paused it, deleted the partition, re-ran bitlocker this time using 'used space only' and it was done within a min or two... Tested speed by uploading/copying a large file, and it was the same speed as i would as my other bitlocker drive.. LIVE AND LEARN !!!! as they say... At least there's a thread out there (i.e this one) that explains it all a little better for people wanting to bitlock their 'new' ext drives. Do the used space only !!! or expect to wait a week or two for it to complete *Smile
    thedoc46, Dec 8, 2016

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