[Xiaomi Redmi Note 5 Pro ROMs, Kernels, Recoveries,] RandomNewbie:
Hey there :) What I'm going to say is surely going to surprise you. I stumbled upon this nasty problem and this drove me really crazy. It's definitely not fixed (unless something else triggered this before), but after so much frustration and testing I found the root of this evil. This problem with the System UI freeze and heavily degraded performance while lots of data are transfered over WiFi occurs when you set and activate a mobile data limit, especially a low one. For instance, if you set Android should warn you at 70 MB and cut off the connection at 90 MB, the System UI will definitely freeze while loading lots of data over WiFi. From what I have observed, the system overwhelms itself with calculating the transfered data and thus leads to this issue. This problem did not occur for me when I set a data limit in GB, not MB. But for sure this never occured once I turned the limits off! With the help of an app called MatLog, I spotted that I had literally thousands of lines all the time when the System UI frooze due to this. You can see it by looking at the milliseconds:

09-27 06:13:09.270 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.270+02:00[Europe/Berlin]

09-27 06:13:09.276 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.275+02:00[Europe/Berlin]

09-27 06:13:09.282 D/RecurrenceRule(1974): Cycle 20 from 2018-09-22T00:00+02:00[Europe/Berlin] to 2018-10-22T00:00+02:00[Europe/Berlin]

09-27 06:13:09.282 D/NetworkStats(1974): Resolving plan for NetworkTemplate: matchRule=MOBILE_ALL, subscriberId=262075..., matchSubscriberIds=[262075...]

09-27 06:13:09.286 D/NetworkStats(1974): Found active matching subId 1

09-27 06:13:09.296 D/NetworkStats(1974): Resolved to plan null

09-27 06:13:09.300 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.299+02:00[Europe/Berlin]

09-27 06:13:09.303 I/zygote64(22643): Do full code cache collection, code=251KB, data=146KB

09-27 06:13:09.304 I/zygote64(22643): After code cache collection, code=245KB, data=137KB

09-27 06:13:09.305 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.305+02:00[Europe/Berlin]

09-27 06:13:09.310 D/RecurrenceRule(1974): Cycle 20 from 2018-09-22T00:00+02:00[Europe/Berlin] to 2018-10-22T00:00+02:00[Europe/Berlin]

09-27 06:13:09.311 D/NetworkStats(1974): Resolving plan for NetworkTemplate: matchRule=MOBILE_ALL, subscriberId=262075..., matchSubscriberIds=[262075...]

09-27 06:13:09.313 D/NetworkStats(1974): Found active matching subId 1

09-27 06:13:09.319 D/NetworkStats(1974): Resolved to plan null

09-27 06:13:09.326 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.326+02:00[Europe/Berlin]

09-27 06:13:09.331 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.331+02:00[Europe/Berlin]

09-27 06:13:09.336 D/RecurrenceRule(1974): Cycle 20 from 2018-09-22T00:00+02:00[Europe/Berlin] to 2018-10-22T00:00+02:00[Europe/Berlin]

09-27 06:13:09.336 D/NetworkStats(1974): Resolving plan for NetworkTemplate: matchRule=MOBILE_ALL, subscriberId=262075..., matchSubscriberIds=[262075...]

09-27 06:13:09.339 D/NetworkStats(1974): Found active matching subId 1

09-27 06:13:09.345 D/NetworkStats(1974): Resolved to plan null

09-27 06:13:09.348 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.347+02:00[Europe/Berlin]

09-27 06:13:09.354 D/RecurrenceRule(1974): Resolving using anchor 2018-09-27T06:13:09.354+02:00[Europe/Berlin]

09-27 06:13:09.359 D/RecurrenceRule(1974): Cycle 20 from 2018-09-22T00:00+02:00[Europe/Berlin] to 2018-10-22T00:00+02:00[Europe/Berlin]

09-27 06:13:09.360 D/NetworkStats(1974): Resolving plan for NetworkTemplate: matchRule=MOBILE_ALL, subscriberId=262075..., matchSubscriberIds=[262075...]

09-27 06:13:09.362 D/NetworkStats(1974): Found active matching subId 1

09-27 06:13:09.368 D/NetworkStats(1974): Resolved to plan null

This affects LineageOS and similar ROMs too, like crDroid.

There is also another issue which I spotted, and has to do with LineageOS as well. If you go to "Trust" and set one of the privacy permissions that the system should ask you, the system will completely freeze once such a dialog would pop up. You can test this by selecting that you will be prompted if MiXplorer may access the external storage. Once this happened, you can only turn off the screen, but that's it. A force-restart is necessary.

---------- Post added at 02:35 AM ---------- Previous post was at 02:28 AM ----------

Hey, do you mind if you can tell how battery drain is while playing the game? When I play the game on medium graphics and medium framerate, it drains roughly 25% per hour. I'm just wondering if this is normal, as I haven't found any exact statistics with battery life and gaming, only average screen on time. Because I suppose it would also mean that drain goes even higher on HD graphics and high framerate :/ Thank you in advance!