I have a twist mini s431 (512MB RAM, MediaTek MT6580 1.3GHz Quadcore) running Android 8.1. It seems this model is only sold on Brazil.
I was extremely unsatisfied because of it's slowness.
I read a lot of complaints about it but no solution.
I found a generic way that I will answer here.
Pt-br Keywords to help ppl here find this post: lento, trava, demora muito (other suggestions?)
(I must say that this below is not a perfect solution yet, as one or more of the disabled apps below made "goggle play store" stop working but I still have no idea which ones, therefore I ended unable to update apps... and had to reset them all... I will re-do disable slower to know what needs to remain enabled)
The answer is: you have to disable as many bundled applications as possible, including system applications.
This can be done by any user but WITH CAUTION!
As I understand it, you cant disable system applications related to the hardware like managing the sdcard, or related to the carrier, or things like bluetooth or wifi etc. I don't know tho if there are other special system applications that should be kept enabled (even if it is allowed to disable them). If you can give some more advisement about this, I appreciate it.
If anyone is interested on what I disabled, I will try to connect on it with adb shell to list all disabled applications, or at least specify what you shall never disable.
So my "twist mini s431" is not fast, but is finally usable now!
PS.: I would like to write all this also in portuguese and paste here as alternative reading, but I think it is not allowed, so use google translator if needed!
The list of packages I disabled (adb shell command), but I haven't booted it yet (I can't boot it w/o being sure it won't fail), so I am not sure this list is boot safe:
$ pm list packages -d
package:com.android.providers.calendar
package:com.google.android.onetimeinitializer
package:com.google.android.apps.mapslite
package:com.android.protips
package:com.android.htmlviewer
package:br.com.positivo.appstore
package:com.netflix.partner.activation
package:com.mediatek.omacp
package:com.android.vending
package:com.google.android.marvin.talkback
package:com.android.statementservice
package:com.vantera.cbwidget
package:com.google.android.apps.tachyon
package:com.google.android.apps.searchlite
package:com.google.android.apps.nbu.files
package:com.android.musicfx
package:com.android.chrome
package:com.google.android.gsf
package:com.google.android.ims
package:com.google.android.tts
package:com.android.calllogbackup
package:com.google.android.partnersetup
package:com.netflix.mediaclient
package:com.google.android.feedback
package:com.google.android.printservice.recommendation
package:com.google.android.apps.photos
package:com.google.android.calendar
package:com.mediatek.calendarimporter
package:com.mediatek.webview
package:com.google.android.apps.speechservices
package:com.google.android.apps.photosgo
package:com.google.android.apps.assistant
package:com.android.providers.userdictionary
package:com.google.android.apps.youtube.mango
package:com.google.android.inputmethod.latin
to see memory usage: adb shell dumpsys meminfo
