I'm basically compiling some interesting stuff I've found hunting through these boards because it appears every Windows Phone I've upgraded to the 8.1DP (except the 520, strangely) has been getting issues that make it impossible to use. On my Lumia Icon, it would overheat and the power button would start having 3-9 seconds of delay when on WiFi. Using diagnostics I must've sent at LEAST fifty error reports with nothing being fixed... but there are some very helpful people I've run into here and there that gave me solutions that I'd like to share.
Solution #1: Open EVERY App Installed On Your Phone
From what I understand, apps do need to be initialized so that they don't cause problems. It sounds illogical that people would have apps installed that they haven't even used once, but
the user response for this has been too much to ignore. While this wasn't a solve-all solution, it made the situation much more bearable when I had my Lumia Icon.
Solution #2: Unpin Cortana's Live Tile From Your Start Screen
Unpinning Cortana was something I first heard of from the user
Kurtis Fox in
this thread. I'm not exactly sure how the Cortana live tile has anything to do with it, but the moment I unpinned it, my 1520 stopped idle-overheat-battery-draining, and the indefinite "Loading...","Resuming..." that occurred after unlocking stopped as well! After so many people told me it was due to low reception areas I was overjoyed to find that was not the case. Regardless of signal, my phone's been staying cool to the touch until I decide to game on it. I halfway wish I still had my Lumia Icon so I could see if this solved the daily overheating I had.
Solution #3: Block The Background Process For All Games By "Gameloft"
Gameloft; while once being humble copy-cat artists, have turned into the exact kind of poison that can make your phone unusable. Even though they take IAP way too far, they spit out a quality game every now and then... but at the same time they are the absolute worst about murdering your battery with non-stop toast notifications and heavy background processes. Go into battery saver and make sure nothing by this publisher is allowed to run in the background.
Solution #4: Assure none of your email accounts' refresh is set to "based on my usage"
This option is a gargantuan battery monger, and has two different ways in which it can wreck havoc on your device. Go into your settings, email+accounts and set the drop down menus for both "Download new email" and "Sync contacts and calendar" to something (ANYTHING!!!) other than based on my usage. I prefer to have mine set to "every 2 hours" and it works swell for me.
Solution #5: Set Up "Kid's Corner"
This is especially helpful if you unlock your device and are treated to a screen that says "Resuming..." very often. This basically resets your lock screen and gets rid of whatever cached data is causing your device to be constantly bludgeoning you with screens that take away from the super-fast, snappy and responsive nature of WP8.1. Swipe down to access your notification bar, tap "All Settings," then scroll down until you see "Kid's Corner". Go through the process of setting it up with a couple apps just to establish it. Test to assure it's been setup properly, then you can go right back into your settings and turn if off if you so desire. This should; at the very least, cut down the amount (if not totally eliminate) the "Resuming..." / "Loading..." screens
...any more tips will be added with due credit. I'll try to keep it visible (possibly even get it stickied?).