How does BitLocker affect performance

Question

I m an ASP NET   C  developer  I use VS2010 all the time  I am thinking of enabling BitLocker on my laptop to protect the contents  but I am concerned about performance degradation  Developers who use IDEs like Visual Studio are working on lots and lots of files at once  More than the usual office worker  I would think   So I was curious if there are other developers out there who develop with BitLocker enabled  How has the performance been  Is it noticeable  If so  is it bad   My laptop is a 2 53GHz Core 2 Duo with 4GB RAM and an Intel X25-M G2 SSD  It s pretty snappy but I want it to stay that way  If I hear some bad stories about BitLocker  I ll keep doing what I am doing now  which is keeping stuff RAR ed with a password when I am not actively working on it  and then SDeleting it when I am done  but it s such a pain    2015 Update  I ve been using Visual Studio 2015 on my Surface Pro 3 when I travel  which has BitLocker enabled by default  It feels pretty much like my desktop  which is an i7-2600k   4 6 GHz  I think on modern hardware with a good SSD  you won t notice

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Some practical tests      Dell Latitude E7440 Intel Core i7-4600U 16 0 GB Windows 8 1 Professional LiteOn IT LMT-256M6M MSATA 256GB   This test is using a system partition  Results for a non-system partition are a bit better   Score decrease  Read  5  Write  16   Without BitLocker     With BitLocker     So you can see that with a very strong configuration and a modern SSD disk you can see a small performance degradation with tests  I don t know what about a typical work  especially with the Visual Studio

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With my T7300 2 0GHz and Kingston V100 64gb SSD the results are     Bitlocker off   on      Sequential read 243 MB s   140 MB s      Sequential write 74 5 MB s   51 MB s      Random read 176 MB s   100 MB s      Random write  and the 4KB speeds are almost identical    Clearly the processor is the bottleneck in this case  In real life usage however boot time is about the same  cold launch of Opera 11 5 with 79 tabs remained the same 4 seconds all tabs loaded from cache   A small build in VS2010 took 2 seconds in both situations  Larger build took 2 seconds vs 5 from before  These are ballpark because I m looking at my watch hand   I guess it all depends on the combination of processor  ram  and ssd vs hdd  In my case the processor has no hardware AES so compilation is worst case scenario  needing cycles for both assembly and crypto   A newer system with Sandy Bridge would probably make better use of a Bitlocker enabled SDD in a development environment   Personally I m keeping Bitlocker enabled despite the performance hit because I travel often  It took less than an hour to toggle Bitlocker on off so maybe you could just turn it on when you are traveling then disable it afterwards   Thinkpad X61  Windows 7 SP1

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I am talking here from a theoretical point of view  I have not tried BitLocker   BitLocker uses AES encryption with a 128-bit key  On a Core2 machine  clocked at 2 53 GHz  encryption speed should be about 110 MB s  using one core  The two cores could process about 220 MB s  assuming perfect data transfer and core synchronization with no overhead  and that nothing requires the CPU in the same time  that one hell of an assumption  actually   The X25-M G2 is announced at 250 MB s read bandwidth  that s what the specs say   so  in  ideal  conditions  BitLocker necessarily involves a bit of a slowdown   However read bandwidth is not that important  It matters when you copy huge files  which is not something that you do very often  In everyday work  access time is much more important  as a developer  you create  write  read and delete many files  but they are all small  most of them are much smaller than one megabyte   This is what makes SSD  snappy   Encryption does not impact access time  So my guess is that any performance degradation will be negligible          Here I assume that Microsoft s developers did their job properly

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I used to use the PGP disk encryption product on a laptop  and ran NTFS compressed on top of that      It didn t seem to have much effect if the amount of disk to be read was small  and most software sources aren t huge by disk standards   You have lots of RAM and pretty fast processors  I spent most of my time thinking  typing or debugging    I wouldn t worry very much about it

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The difference is substantial for many applications   If you are currently constrained by storage throughput  particularly when reading data   BitLocker will slow you down     It would be useful to compare with other software based whole disk or whole partition encryption like TrueCrypt  which has the advantage if you dual boot with Linux since it works for both Windows and Linux    A much better option is to use hardware encryption  which is available in many SSDs as well as in Hitachi 7200 RPM HDD   The performance of encrypted v  not is undetectable  and the encryption is invisible to operating systems   If you have a decent laptop  you can use the built-in security functions to generate and store the key  which your password unlocks from the encrypted key storage of the laptop

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Having used a laptop with BitLocker enabled for almost 2 years now with more or less similar specs  although without the SSD unfortunately   I can say that it really isn t that bad  or even noticable  Although I have not used this particular machine without BitLocker enabled  it really does not feel sluggish at all when compared to my desktop machine  dual core  16 GB  dual Raptor disks  no BitLocker   Building large projects might take a bit longer  but not enough to notice   To back this up with more non-scientifical  proof   many of my co-workers used their machines intensively without BitLocker before I joined the company  it became mandatory to use it around the time I joined  even though I am pretty sure the two events are totally unrelated   and they have not experienced noticable performance degradation either   For me personally  having an  always on  solution like BitLocker beats manual steps for encryption  hands-down  Bitlocker-to-go  new on Windows 7  for USB devices on the other hand is simply too annoying to work with  since you cannot easily exchange information with non-W7 machines  Therefore I use TrueCrypt for removable media

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My current work machine came with bitlocker  and being an upgrade from the prior model   It only seemed faster to me   What I have found  however  is that bitlocker is more bullet proof than truecrypt  when it comes to accurately laying down the data   I do a lot of work in SAS which constantly writes backup copies to disk as it moves along and shoots a variety of output types to disk at the end   SAS works fine writing output from multithreaded processes back to bitlocker and doesn t seem to know it s there   This has not been the case for me with truecrypt   I m not sure what happens or how  but I found that processes got out of synch when working with source output data in a truecrypt container  which is what I installed on my second work computer since it had no bitlocker   The constant backups were shooting to an SSD while the truecrypt results were on a regular HD   Maybe that speed difference helped trip it up   Whatever the cause  I had to quit using truecrypt on that second computer because it made my SAS results out of synch with respect to processing order and it screwed up some of my processes and data   Scary stuff in my world   I work with people who have successfully used Truecrypt on the exact same computer  but they weren t using a disk intensive app  like SAS   Bitlocker to Go  the encryption which bitlocker applies to thumb-drives  does slow things down quite a bit when it comes to read write times   It s not too hard to use as long as you remember your password on the thumbdrive  and are willing to wait for it to format initialize the drive  but in my experience it made access to the flash drive about 4 times as slow   Don t know why it would slow down a thumb drive and not a disk but that s how it was for me and my coworker   Based on my success with bitlocker at work  I bought Windows Pro for my home computer to get bitlocker and plan to encrypt some directories with it for things like financials

[encryption] How does BitLocker affect performance?

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