I agree with ashely and others, not sure if my response will help, but here is a step by step what to optimize if your game has cpu usage issues.
So here are my tips:
1. optimize your event sheet, make sure u trigger once the events and not on a loop or multiple loops.
(you can use loops, but under a trigger once condition, like generate on a loop a certain amount of monsters in a circle for example, or check on start of layout a array database xy etc)
2. you don't need 1080p on mobile games... max image quality u need is 512px anything above that is pointless(if you are not releasing for tablets which might need a 1080p resolution so your games graphic doesn't look choppy --- you can separate assets loading based on devices. however id just keep 512px and just stretch content a bit + a zoom in to match the screen of tablet device), and will just ruin ur gpu performance, making the gpu of the device work overtime for no reason.(after u export find the spritesheet or the assets u have and run them trough tinypng.com once... it will clear some "ghost" shades from it, and cut out the extra dead weight that u actually don't need, like pixel perfect shading transparency extra layers etc)
3. turn the webgl effects off if u can replicate them with normal sprites (webgl heats things very fast in Construct, even if u don't use effects, having webgl activated inside ur game will heat things up for no reason -- there might be a reason but i think this list is just going to be to long ... u can guess what the reason is).
4. don't use 3rd party wrappers, try and wrap ur APK or IOS launcher as native as possible (latest C3 i think does this pretty amazingly good, any outside wrapper is just overcomplicating ur process and dependencies), don't use 3rd parties like the old ones we had ... they are a mess, learn to wrap ur own with android sdk is rather easy, to sign and release a certificate.
5. make sure u export for latest android and not some old android version, sure older android versions might make ur game compatible with older devices, but then ... lots of glitches will be reported, cause the android version is out of date or soon to be dumped from the service maintenance, plus old devices = more weird problems.
6. this sort of goes into nr 2... but is related to audio ... make sure u have the small size exact what u need as sound and music, dont add mp3,ogg,vobb,+++ 1000 other formats inside ur game one game will be huge, 2 u only need ogg for cross compatibility or mp3.
7. if ur running in app purchases or advertisements... make sure u don't over-call them, this sort of goes into 1).
8. Optimize ur event sheet ... i noticed that more than 30 event lines per event sheet is going to create a issue.
9. Optimize ur event sheet ... You can have more event lines by just separating ur events into more eventsheets like (Audio calls, button triggers, global variables, end game, score game, etc), just include them and trigger them when needed.
10. Optimize ur event sheet ... no more than 5 subevents and 10 actions per event line. the more u have the more cpu will consume cause of how many things the computer has to check in that 1 fraction of a second before he moves to the next condition event.
If you would be reading the blogs on optimizations, you would see that the longest and difficult part of game development is optimization. and this step is the most important when comes to having a "good product". That is why i always recommended when going into a "big product for public" make sure u design and code your game from the beginning "optimize in mind". otherwise once u finish it 1 year later, you have to go back to beginning and redo all the code.
Hope it helped, but i doubt i said anything helpful in here that you didn't already knew.
As per device heating up as Ashley said, and i think newton also.... for every action there is a reaction, so cpu/gpu is used (especially on a 80% usage cpu) u will have a reaction out of ur device = heat ... ur mobile game ideally should sit at 0-15% usage idle (CPU+GPU) and ~50% on triggers and rendering. not 70% all the time.