Issue: LR Classic performance on macOS x86_64 drops when a 2nd screen is connected
Lightroom Classic version: 12.0.1 [ 202210260744-9e008017 ]
OS and version: macOS 12.6.1 (21G217)
Machine: iMac (Retina 5K, 27-inch, 2017), 24 GB RAM, Radeon Pro 580 8 GB
Steps to reproduce:
1. Connect a second monitor (in my case a Dell U2212HM)
2. Run LR Classic and edit photos in Develop, note performance especially when adding a few masks; mouse pointer often gets sluggish. Performance marginally improves when disabling other panels, i.e. Detail and Lens Corrections, but remains low and sluggish. The fan often spins up briefly when using brushes. Performance is low even if the second monitor shows no LR Classic windows (in my case just macOS's desktop)
3. Quit LR Classic, no need to reboot the machine
4. Disconnect the second monitor
5. Reopen LR Classic and keep editing, note performance increases and is on par with what the machine should support, even with all other develop panels enabled. The fan only spins up once in a while on heavier edits.
Expected result: same performance with or without a second monitor
Actual result: just keeping the second monitor connected reduces performance in LR, leading to CPU constantly hitting close to 100% (800% in my case, i7 quad w/ HT). Disconnecting the second monitor restores the expected performance.
Point of note: the internal screen is retina / hi-dpi, the second monitor is not
I understand that these steps are quite empirical and may not be enable to reproduce the issue on other machines. I am able to reproduce it quite consistently on mine, however, and I'm more than happy to provide specific diagnostics, instrument traces or logs that Adobe may require to narrow this down. Note that no other apps seem to exhibit the same issue, not even Photoshop.
LRC's System Info:
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Lightroom Classic version: 12.0.1 [ 202210260744-9e008017 ]
License: Creative Cloud
Language setting: en-IT
Operating system: Mac OS 12
Version: 12.6.1 [21G217]
Application architecture: x64
Logical processor count: 8
Processor speed: 4.2GHz
SqLite Version: 3.36.0
Built-in memory: 24,576.0 MB
Real memory available to Lightroom: 24,576.0 MB
Real memory used by Lightroom: 2,261.7 MB (9.2%)
Virtual memory used by Lightroom: 39,758.7 MB
Memory cache size: 6.7MB
Internal Camera Raw version: 15.0 [ 1261 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 281MB / 12287MB (2%)
Camera Raw real memory: 359MB / 24576MB (1%)
Standard Preview Size: 2880 pixels
Displays: 1) 5120x2880, 2) 1920x1080
Graphics Processor Info:
Metal: AMD Radeon Pro 580
Init State: GPU for Export supported by default
User Preference: Auto
Application folder: /Applications/Adobe Lightroom Classic
Library Path: /Volumes/Crucial/LR/Lightroom Catalogs/Daniele Nicolucci 2020/Daniele Nicolucci 2020-v12.lrcat
Settings Folder: /Users/jollino/Library/Application Support/Adobe/Lightroom
Installed Plugins:
1) AdobeStock
Config.lua flags: None
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macOS's System Profiler:
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Hardware Overview:
Model Name: iMac
Model Identifier: iMac18,3
Processor Name: Quad-Core Intel Core i7
Processor Speed: 4.2 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Hyper-Threading Technology: Enabled
Memory: 24 GB
System Firmware Version: 499.40.2.0.0
OS Loader Version: 540.120.3~22
SMC Version (system): 2.41f2
Radeon Pro 580:
Chipset Model: Radeon Pro 580
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 8 GB
Vendor: AMD (0x1002)
Device ID: 0x67df
Revision ID: 0x00c0
ROM Revision: 113-D000AA-931
VBIOS Version: 113-D0001A1X-025
EFI Driver Version: 01.00.931
Metal Family: Supported, Metal GPUFamily macOS 2
Displays:
iMac:
Display Type: Built-In Retina LCD
Resolution: Retina 5K (5120x2880)
Framebuffer Depth: 30-Bit Colour (ARGB2101010)
Main Display: Yes
Mirror: Off
Online: Yes
Automatically Adjust Brightness: Yes
Connection Type: Internal
DELL U2212HM:
Resolution: 1920x1080 (1080p FHD - Full High Definition)
UI Looks like: 1920 x 1080 @ 60.00Hz
Framebuffer Depth: 30-Bit Colour (ARGB2101010)
Display Serial Number: Y9KCH25L0D0L
Mirror: Off
Online: Yes
Rotation: Supported
Connection Type: DVI or HDMI
Adapter Firmware Version: 7.55
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