[Android Q&A, Help & Troubleshooting] pndwal:
1) For some time now, we've had frustratingly bad performance using LOS14.1 custom ROM on our three Y550 phones in daily use. Apps become laggy and unresponsive, scrolling becomes stuttery, and frequently apps lock up completely and need restarting after minutes of use.

I don't know if others have had this issue, or if any ram management functions have changed fundamentally with LOS updates, but I played with various Magisk modules to try to find a fix.

We had very limited improvement with Android Go Enaber (sets low-ram-property flag in android 4.x and above: https://www.google.com.au/amp/s/xda...module-low-ram-property-patcher-t3740199/amp/ ), or other RAM management mods, ̶b̶u̶t̶ ̶w̶h̶e̶n̶ ̶I̶ ̶e̶n̶a̶b̶l̶e̶d̶ ̶R̶A̶M̶ ̶M̶a̶n̶a̶g̶e̶m̶e̶n̶t̶ ̶F̶i̶x̶e̶s̶ ̶b̶y̶ ̶c̶r̶o̶k̶,̶ ̶w̶e̶ ̶h̶a̶d̶ ̶a̶n̶ ̶I̶N̶S̶T̶A̶N̶T̶ ̶F̶I̶X̶!̶ ̶-̶ ̶n̶o̶ ̶m̶o̶r̶e̶ ̶a̶p̶p̶ ̶f̶r̶e̶e̶z̶e̶s̶,̶ ̶l̶a̶g̶g̶i̶n̶e̶s̶s̶ ̶g̶o̶n̶e̶.̶ ̶:̶)̶ Edit: but when I enabled RAM Management Fixes by crok, we had instant improvement - app freezes, lagginess were reduced and seemed to be solved for a while, BUT STILL OCCURRED.

With further investigation, I discovered the problem actually stemmed from Magisk root. Not sure what component, but with a full cleanup and unroot the phone behaved perfectly again - app freezes, lagginess were gone completely at last.

Next, I fully reinstalled Magisk and modules, and all is still good. :)

Then I disabled RAM Management Fixes by crok, and found there is now NO DIFFERENCE, so I'm concluding that when settings are messed up on a device this mod can and does improve things, but with a normally working Y550 device it offers NO ADVANTAGE. Sorry if previous info posted was misleading :silly: End Edit.

Edit 2: I thought I'd re-enabled Magisk modules, but new installation was actually set to Core Only mode. This is what resolved lag and app crash issues, and turning it off to enable module use immediately destroyed performance, even with all mods toggled off (deactivated) :( .

I'm not sure when this started, but seems many have had the issue for several Magisk iterations, and have found no solution other than to sacrifice modules and use only basic core-only root functions. - There is very little info on official Magisk threads, but heaps of reports and analysis elsewhere, with no other solutions. (My guess is others with issues have low Ram devices like ours. Issue could also be associated with adopted storage use.)

This is a real shame as many mods are very useful. Guess I'll just have to find TWRP flashable alternatives for YouTube Vanced. Viper Audio, Call Recorder etc etc :( .

Summary: Sadly, the only solution for lag and instability with Magisk root on Y550 for now is to RUN IT IN CORE ONLY MODE. Let's hope [MENTION=4470081]topjohnwu[/MENTION] works some magic and fixes it, but don't hold your breath... End Edit 2.

Just thought I'd pass on this fix as it was sorely needed, and should help others experiencing these problems.

[ 2) Other Magisk modules I like include YouTube Vanced - great if you want to listen to YouTube audio (music) with screen off or while using other apps, or if you want an add-free experience without paying Google for the premium version. https://vanced.app/ ]

3) Regarding touchscreen issue:

- With phone plugged in to some chargers, touch screen is erratic and unusable, but with a good quality unit there is no problem. I have a cheap charger (problems), and a multi port Aukey charger (no problem), so good mains noise suppression (absent on cheap units) seems to be required. My guess is that a better laptop power supply will similarly allow phone use while tethered to USB. PW