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I've compressed a disk volume and now I've noticed that disk access (and/or the system as a whole) seems slower

Explanation: Disk compression was installed on the system and a compressed volume created. Using this volume now seems slower than it was before.

Diagnosis: This is a common side effect of using compression and is generally more often the rule than the exception. Compression works by adding a software interpretation layer and this takes processing time compared to just writing the data directly. The slowdown is especially noticeable on PCs with slower processors. On faster processors, compression can in theory improve overall performance by reducing the number of accesses to the (slow) hard disk. Compression performance is discussed in detail in this section of the Reference Guide.

Recommendation:

  • Many compression programs, such as DriveSpace 3 for Windows 95, allow you to tweak the compression level that they use when storing files. You may be able to improve performance (at the cost of the compression level) by changing the compression level settings.
  • Use compression only for applications and data for which performance is not a critical issue. Use multiple partitions and put items requiring top performance in an uncompressed area.
  • If performance is paramount, do not use compression. While I am not dead set against its use, I recognize that it was far more important in the world of the $300 340 MB drive (a few years ago) than in the world of the $300 4 GB drive (today, with prices continuing to drop rapidly).

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