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The uninstall suggestion above solved my problem.

FYI, I discovered that netsession was the culprit (which led me to this thread) as a result of a suggestion on a related thread by user chrisle:

Run the following in Terminal:

sudo fs_usage

That command allowed me to see the huge number of netsession accesses.

iMac 27 (3.06 GHz Intel Core Duo), OS 10.6.8
 
All this happened because I very reluctantly downloaded PhotoShop CS5 trial for a course when I was perfectly happy with Pixelmater but the tutors said I needed Adobe.
No one forces you to use the Akamai download manager. Adobe provides also direct downloads.
 
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