[MacTUG] Tests show that less is more with Parallels

[Marlon A. Griffith]

MacWindows. July 10, 2007 -- Sylvain Jette sent us test results that 
indicate better Parallels Desktop performance with less RAM assigned 
to Windows. Jette also found that this is not the case with iEmulator 
running on an Intel Mac.

This Parallels behavior is not what users have come to expect with 
running Windows on Macs. Ever since the first emulators began 
appearing for Macs, assigning more memory to Windows has been a 
method of increasing performance.

A reader last week said that for Jette's first batch of test results, 
the memory setting was too high. Jette's responed by sending us this 
report:

     After reading Tony Martin's tip on running Parallels with 512 MB 
assigned RAM, I can now say that Parallels is in fact faster booting 
and launching apps with 512 MB than 764 MB rams. There were almost no 
changes for iEmulator.

     iEmulator:

     764 MB of RAM
     Windows XP boot time = 1 minute 15 seconds
     Windows XP shutdown = 15 seconds
     Lauching IE to MSN.com = 15 seconds

     521 MB of RAM
     Windows XP boot time = 1 minute 15 seconds
     Windows XP shutdown = 9 second
     Lauching IE to MSN.com = 15 seconds

     Parallels Desktop:

     764 MB of RAM
     Windows XP boot time = 36seconds
     Windows XP shutdown = 20seconds
     Launching IE to MSN.com = 7seconds

     512 MB of RAM
     Windows XP boot time = 23 seconds
     Windows XP shutdown = 20 seconds
     Launching IE to MSN.com = 5 seconds

Jim Pepe, however, thinks the situation is more complicated:

     I just wanted to point out this may not be accurate: "Parallels 
recommends no more than 512 MB, and in most cases 340 MB should be 
the ideal amount of RAM to give the virtual machine."

     I have been using Parallels since the first Beta, I don't see 
where Parallels recommends no more than 512 MB; I believe it's system 
dependent. This is from the Parallels help file:

     "The Memory Size parameter describes the size of virtual memory 
(RAM) to be allocated for the virtual machine. You can choose any 
value from 4 to 1500 MB. We advise you not to exceed the recommended 
maximum because this is the limit of the physical RAM that your 
system should reserve for virtual machines. If this amount is not 
enough the redundant memory is swapped to disk, thus slowing down 
both guest OS and primary OS performance."

     I believe each size is based on how much RAM the user actually 
has installed. On my machine, Parallels is saying 924 MB is the 
maximum I should use.