Waiting an hour and half for the iso to download only to wait another hour and a half for the update is no fun.
You may want try testing the download sites for speed - its normally suggested to use a mirror close to your actual physical location, which quite often works, but depending on how busy the actual server is that can also have a big hit on download speeds.
I'm in the UK and I always find Heanet.ie is very good for both speed and reliability.
Providing your using a download app that can resume a download it pays to try other download mirrors as you can always "pick up" where you left off.
I find Filezilla very good for this, and I always find it faster than using Firefox.
This above also holds true for repo updates - pick a site close to you and try that (you can always download just a few updates and see how that progresses before doing a major update) if its slow try another.....
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