Should I install Windows 7 Service Pack 1 Update?

I'm a guy who likes to keep all the software on my laptop updated to the latest version (Except Windows updates). Recently I saw on the web that there is a service pack update for Windows 7 named Service Pack 1 and searched more for details about this update and found that many users who have updated to Service Pack 1 are experiencing slowdowns. I have already downloaded the genuine SP1 ISO file for the Ultimate version and hesitating to go for a fresh install because of these bad reviews.
Will a clean install of Windows 7 Ultimate Service Pack 1 (x86) make my computer slower than my current non-SP Ultimate (x86) edition as many users have posted on the internet? If so how can I overcome that problem?
Please help me 

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