Like will it slow down your boot-up?

Also what problems will arise if you allocate more hard drive memory for virtual memory than what is available, will that cause any issues?

  • What kind of "ViM" are you talking about, "virtual memory"? This tag is for Vim, the text editor. For what it's worth, virtual memory is supposed to be some empty space on your hard drive used to offload your RAM. I suppose most OSes will take what is available, no matter what crazy numbers you have set. – romainl Nov 15 '11 at 19:37
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    @romainl : That's a page/swap file. There are systems with page/swap files and no virtual memory and there are systems with virtual memory and no page or swap files. – David Schwartz Nov 15 '11 at 22:35

Allocating extra virtual memory should not slow down boot up, because these page files (on most OSes; you didn't specify) are created once and then just sit there until they are used. They are just a preallocated block.

The only performance delay will be if the OS decides to use them because it has filled all the real memory (RAM), in which case you will experience slowness as your system pages to disk.

If you over-allocate, then your system will behave as if it has more RAM, albeit with this performance penalty that disks are slower than actual RAM.

hope that helps.


If you mean the page files, then, besides taking up space on the hard drive, there are no performance penalties associated with large page files. They will just go underused, and you'll waste space better used for pictures of funny cats or what have you.


The memory management unit manages the virual memory. It translates virtual memory adresses to actuall physical adresses. The bigger the virtual memory space, the bigger the adress table becomes in which is written, which virtual adress belongs to which physical adress. A big table can theoreticaly result in slower translation of the adresses and therefore in slower reading and writing speeds. I can't quantify this effect. Its probably not relevant.


From what I understand, since windows 7 and later, they've gotten good at letting Windows determine the page file size, so I would check the box to do it automatically.

  • You are correct about that, @James. I'd just add that every effort should be made to avoid the use of the pagefile at all. So my VMs are sized appropriately so that everything fits in RAM, since the pagefiles are about 10,000 times slower if on a hard drive. If your VMs and other applications can't fit then the slowdown can make you wonder if your computer has failed. But usually you can wait it out (if it is important) or shut it down and try again with a more appropriate size. – SDsolar Jun 24 '17 at 7:21

Aside from Virtual Memory being slower than RAM another issue is slower i/o speed to the hdd (which is often the bottleneck in performance anyway) and you run the risk of burning through a hdd much faster.

  • It makes no sense to compare the speed of virtual memory to the speed of RAM. – David Schwartz Nov 15 '11 at 22:36
  • If he wants to know if there are any performance penalties to allocating more VM then he should be aware that it will not behave the same as adding more RAM. – Zombian Nov 15 '11 at 23:30
  • Except that's not what he wants to know. He wants to know about adding more page/swap. You can't really add more virtual memory to Windows. – David Schwartz Nov 15 '11 at 23:58

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