Macbook slow since latest update last week

Since the latest update from MAC last week, I've had nothing but problems with my Macbook and so has my sister who has one and my daughter who has a pro. All of us have had internet and applications problems since we all updated the latest update.
Anyone know what the problem is and how to fix it?
Thank you ever so much

Reply 1 : Macbook slow since latest update last week

what version of OS X are you using?

What, exactly, did you update?


P