Sadly, the stuttering is back after I completely reflashed the device.
With Claude AI's help, I spent a long time analyzing my logs because I don't know much about this.
Current issue: stutter that comes back with uptime. After the reflash the ANRs stopped, but the UI still stutters. Measurements from SystemUI at 1.6 days uptime: (only with 2 SIMs activ, when i disable one of it, its smooth)
587 MB RSS, 137 MB graphics, 113 MB Dalvik heap of a 256 MB limit
GPU exceeded the 8.3 ms frame budget on 2.29% of frames
Two measured 1 s freezes (33 and 108 skipped frames) each occurred within 10 ms of a Background concurrent mark compact GC in SystemUI
What I tried, and what it actually showed. I switched display resolution from "max" back to "high" (which is the factory default here. Measured effect at 3 days uptime:
Graphics memory: 137 MB → 47 MB
GPU frames over 6 ms: 5.6% → 3.0%
Dalvik heap: unchanged at 112 MB
Slow UI thread: 1.72% → 2.16%, overall jank 1.97% → 2.37%
It felt smoother for a couple of days and then went back to exactly how it was before. Since changing resolution restarts SystemUI, I now think the improvement came from the restart rather than from the resolution. The memory saving was real but apparently not the cause.