slow performance on Parallels

Discussion in 'Windows Guest OS Discussion' started by rgl, May 10, 2007.

  1. rgl

    rgl Bit poster


    I currently have Parallels on a Dell Latitude D820 (Core 2 Duo T7200, 1GB RAM, 120GB SATA drive). I did a clean install of Windows Vista Business on the drive, update all patches, and installed Parallels on the machine (latest release available on website). What I found is that the XP virtual machine is running quite slow, noticeably slower than VMWare. I have even disabled Aero but did not notice much improvements.

    What I found is the following: I was doing Windows update on the XP VM. There is a total of 73 patches to be done; after one hour I am still on the 38th patch. The VM CPU is busy constantly (almost 100% all the time), yet the physical CPU (both cores) is running only at 15%, 10%, sometimes even less (single digits).

    The network is very fast here at work, so downloading speed is not an issue. I gave the XP VM 384MB RAM. All other things are default, acceleration is on High. On the host Vista OS, the only extra thing that I have put on extra is Intel chipset software and Adobe Reader 8. No other software are loaded at the moment, and no networking are configured except basic TCP/IP. Parallels Tools are loaded on the VM.

    Is there something wrong with the performance or configuration of Parallels? I have included the screenshot of both Task Managers in this messages.

    Attached Files:

  2. fullblown

    fullblown Bit poster

    Strange how you vista Task Manager shows 2 CPU Treads low but on your XP version one maxed out.
  3. mmischke

    mmischke Hunter

    Vista's Task Manager shows that nearly all of its physical memory is committed. That's never a good scenario. With only 1 GB of physical RAM, you'll want to disable any and all UI glitz on both the guest and host (Vista widgets, too). Keep in mind that both Vista AND XP want RAM. Lots of it. You've only got 1 GB to share between them. I know that some folks here will disagree with me, but I don't feel that virtualization is a viable option unless a machine has at least 2 GB of physical RAM. 1 GB _may_ be OK if both guest & host are highly tweaked for performance, but in many common scenarios it's virtual memory paging that puts a drag on performance.

    Try temporarily making Vista and XP look more like Windows 2000. I suspect you'll see a big difference...
  4. LinkRS

    LinkRS Member

    Hi Rgl and Mmischke,

    Vista uses RAM differently than XP does. If you look at the Vista task manager, you see both "cached" and "free" RAM totals. In terms of available program memory, you count both the free and the cached. Vista will try to keep all of your RAM busy, as it makes it perform faster if it can pull something up out of RAM. However, running both Vista on 1 GB and XP on 384 MBs of RAM is sub-optimal at best. Vista performs "best" when it has 1 GB of RAM all to itself, and since Parallels is "taking" 384 MBs for the VM, Vista is RAM starved. If you are gonna run Vista, it is highly suggested to go up to 2GB, and if you are going to run a VM, it is even more important. My desktop has 2GBs, and I give 768 MBs to my XP VM, and it runs OK, not native but OK. Try adding some more RAM to the Latitude.

    Rich S.

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