Fix for Hyper threading in WinXP SP1

SYMPTOMS

A program that uses large mapped file views to share information between two processes

may experience a significant performance decrease. The performance degradation

occurs in the UnmapViewOfFile function. CAUSE

This problem occurs if you install Windows XP Service Pack 1 (SP1) on an Intel

Pentium 4 computer that has more than one logical processor. RESOLUTION

A supported fix is now available from Microsoft, but it is only intended to

  correct the problem that is described in this article. Apply it only to computers

  that are experiencing this specific problem. This fix may receive additional

  testing. Therefore, if you are not severely affected by this problem, Microsoft

  recommends that you wait for the next Windows XP service pack that contains

  this fix.

To resolve this problem immediately, contact Microsoft Product Support Services

  to obtain the fix. For a complete list of Microsoft Product Support Services

  phone numbers and information about support costs, visit the following Microsoft

  Web site:

Download

  the fix Q815227 Hyper-Threading Update

More

  Info…

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