Thanks for the confirmation, indeed 4GB might have been too low at times. I remember I had such problems when I was testing game on the default Mono architecture (I have 8 GB of ram on my phone), After I switched it worked quite well although I've never worked on a 4GB phone with the build. I'll try to decrease the function call amount over the next few updates so that the game's performance doesn't degrade too much in the future when it has more content!
Take care and have a good one!