I don't think it will make your computer run faster, it will just free up space. If you have available space, don't compress. If you access a compressed file in the future, it may take longer to open/run.

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Present - 2006 X3
Present - 2003 Z4
Past - 2001 740il
Past - 2001 R1150RT
Past - 2000 Volvo S80