The Wall Street Journal is reporting that Apple has begun “looking into” issues that are being reported from iPhone 3G users running iOS 4 on their Apple device. Discussion boards across the entire Internet are exploding with complaints and issues with iOS 4 and iPhone 3G users (Apple Discussion), with claims of poor system performance and stability, battery drains, and overheating.

The most common criticism is that the phone is slow after an upgrade. There are also many complaints that the phone drains the battery quickly and becomes excessively hot. Concern about general problems such as slowness and battery life on gadgets isn’t unusual, but using iOS 4 on the iPhone 3G seems to make the problems so bad that the phone is nearly unusable for some people.

Some frustrated users have even gone as far as creating parody videos of poor iOS 4 performance on the iPhone 3G (one is below):

There have been reports that these issues are somewhat being correct in iOS 4.1, which is currently in a beta stage.

Apple made it clear that the iPhone 3G would not be able to support some of the new features coming in iOS 4, such as multi-tasking and homescreen wallpapers. It appears as though, even without these features, the iPhone 3G is still being pushed to its limit with iOS 4.