Apparently, The Xperia Z3+ from Sony is plagued by an overheating issue. What makes this unsurprising is that it sports the Qualcomm Snapdragon 810 processor. Sony recently issued a statement on the subject,
“The Xperia Z3+ is a high-performance 64-bit octa-core device with advanced camera technology, in some cases, additional heat can cause functions to stop. Enabling applications can also be felt by the user through the glass on the back. This is normal for the unit and should cause no concern.”
Sony also confirmed that they would be releasing a software update later this summer to address the issue, but that will likely be some for of CPU throttling rather than a real fix.
It's very likely that Qualcomm is looking forward to bringing their next-gen Snapdragon 820 processor to market as soon as possible to put the fiasco of the 810 to rest.
Source: Xperiablog