I just completed a heat test with my 350. I sat outside in the shade, no sunlight ever touched the reader, for an hour with the temperature at 90 degrees F, the humidity at 45%, and the heat index at 93 degrees. The entire time I had the 350 on and was reading a 1426 page ePub book at my normal pace. The reader was inside a Case Logic padded case during the test. In retrospect I probably should have removed it from this case as it is heavily padded and thus provides some degree of insulation to the back and sides. But I did not want to drop my 350 naked onto concrete!

I read for about 40 minutes before I became aware that the 350 might be slowing down as far as page turn speed. By the end of the hour the slow down was indeed quite noticeable. I came back inside and did my best to time the page turning speed with a stopwatch, though I found that difficult. But my best guess is that from initial finger contact to begin the swipe through the page turn was appx. 1.5 seconds. I was doing very fast swipes. The page turns were slow enough that the process of inverting the screen was extremely visible. That is, the screen turns black with light lettering then turns light with black lettering for the new page. The black screen seemed to last quite a while. I'm not sure what a normal speed is when page turning, but it takes considerably less time.

However, I can live with 1.5 second page turns when in the heat as I will seldom be reading in that temperature. No other slow down or erratic behavior was noticed. At worst, I find this to be a very minor issue.

Since the K3s also exhibit this issue, I have to think it might be the Pearl screen. I doubt that the K3 and 350 use the same processor, but if they do that could be the problem as well--if processor gets too hot it might slow down the system. I have not tried this test with my K3 yet, but I probably will soon. Note, the K3 page turns are probably twice the speed of the 350 when I do side by side comparisons using the same book on each.