[QTBUG-52372] QML Rendering performance issues with multiple windows - Qt Bug Tracker

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Details

Type: Bug
Status: Open
Priority: P1: Critical
Resolution: Unresolved
Affects Version/s: 5.6.0
Fix Version/s: None
Component/s: GUI: Graphics Performance
Labels:
None
Environment:

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Model Name: MacBook Pro
  Model Identifier: MacBookPro11,3
  Processor Name: Intel Core i7
  Processor Speed: 2,8 GHz
  Number of Processors: 1
  Total Number of Cores: 4
  L2 Cache (per Core): 256 KB
  L3 Cache: 6 MB
  Memory: 16 GB

Chipset Model: NVIDIA GeForce GT 750M
  Type: GPU
  Bus: PCIe
  PCIe Lane Width: x8
  VRAM (Total): 2048 MB

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Model Name: MacBook Pro   Model Identifier: MacBookPro11,3   Processor Name: Intel Core i7   Processor Speed: 2,8 GHz   Number of Processors: 1   Total Number of Cores: 4   L2 Cache (per Core): 256 KB   L3 Cache: 6 MB   Memory: 16 GB Chipset Model: NVIDIA GeForce GT 750M   Type: GPU   Bus: PCIe   PCIe Lane Width: x8   VRAM (Total): 2048 MB

Description

The attached project opens 16 Qt Quick windows. Each is of them displaying a small (27kb) image which is rotated by an RotationAnimator.

I observe continuous frame drops. The animation is stuttering. With an increased windows size the issue already starts with 8 windows. CPU performance according to activity monitor is above 140%.

Note: profiling didn't point to any obvious scene-related hotspots. Animations frame-rate is 60 fps. I see a lot of time spent in the SG swap state. The graphics card should be able to draw these scenes without frame-drops.