I should mention that I also avoid using the tiny USB flash drives barely bigger than a USB A connector because they tend to have heat and performance issues.
+1. The Nano and Micro compact flash drives and WLAN adapters, too. I have a SanDisk Cruzer Nano USB 3.0 that gets so hot after a couple GB writes, you can hardly hold it between the fingers to remove it! In fact I just stopped using it because I figured that much heat, premature failure is inevitable.