So I just got my S4 last night and used Samsung Smart Switch to transfer my stuff from my iPhone to the S4, including my texts. My messages app is so slow that I can barely text. When I open a conversation sometimes it doesn't even load, and the app keeps crashing. I don't know if it's doing this because of the amount of texts I have or not, but I don't see why it wouldn't be able to handle it considering I had all of those texts on my iPhone. I really like the phone besides this major issue :/ any help is appreciated. The phone also gets really hot while charging and moderately hot sometimes during use.
The heating is standard with any mobile device including the iphone, the glass and aluminum just do a really good job of evenly dissipating it. It gets hot on charge because current is being applied to the device, while the mini transformer you plug into the wall does a good job, the usb receiver on the inside of the device still has to finish converting it to be usable by the device.
As for the messaging app, you could always try a third party messenger, like "whats app", or "go messenger". I'm unsure of what type of file the iPhone uses to store texts in, but the Smart Switch program may not correctly convert all of them to the type used by the S4, which may be what is causing the crashing. But a better question would be; why store all of those texts anyway? Android has a feature built into the stock messenger (of which all manufacturer messengers are based), that automatically deletes the oldest stored text messages from the device once the user defined limit is reached (I believe it is set at 150 per contact with stock settings).
Believe it or not, storing lots of text messages, and similarly call logs on your phone, can actually cause the respective apps to start malfunctioning. This is because the old data conflicts with the new data that is being stored in the same app cache, especially if it comes from a non native source, as I mentioned earlier.
So once again my suggestions to you would be to...
1) Try a different messenger and see if it fixes it.
OR
2) Trim down some of your messenges.