iPhone 3G users who are experiencing sluggish performance and even overheating when using their device with iOS4 will be happy to know that Apple is investigating the cause of the issue.
According to Wall Street Journal Blog Digits, a company spokeswoman told them that they are aware of the issue and are looking into the matter. Complaints on Apple's support forums have grown to include slowness after the upgrade, quick battery drain as well as the unit getting excessively hot.
I only had my iPhone 3G with iOS4 for about a week or so before I got the iPhone 4, but I didn't experience the slowness that others have, nor did the phone get any hotter than normal. My battery power level seemed to be about the same but for a 2 year old phone that got heavy use, it wouldn't be a surprise if it was time to change the battery.
For those that want to dump iOS4, Lifehacker has a tutorial on how to do just that.
We'll wait and see what apple does to fix this.
I live in Brazil, and as soon as I had the option to upgrade theOS, did so. CONFIRM overheating of the device, sluggishness, poor reception, and a speedy drain of the battery. I now use the 3G with the wireless turned OFF, and it has improved a little, but ondering returning to previous OS. However, changing - upgrading was extremely traumatic: I lost ALL my contacts, and am still unhappy about that.