Confirming with my master build 6.0alpha1.

The main lag seems to appear for me in the handling in bitmap.cxx, line 945:

    Bitmap aBmp(GetBitmap(aDstRect.TopLeft(), aDstRect.GetSize()));

which is called by function :

void OutputDevice::DrawDeviceAlphaBitmapSlowPath(const Bitmap& rBitmap, const AlphaMask& rAlpha, tools::Rectangle aDstRect, tools::Rectangle aBmpRect, Size& aOutSize, Point& aOutPoint)

Please try this with a developer build from https://dev-builds.libreoffice.org/daily/master/ [*]. Check with option Tools->Options->View->Use Skia for all rendering both enabled and disabled, and when enabled with both Force Skia software rendering enabled and disabled.

And is this a duplicate of bug #120727?

[*] Today's build may still have some rendering problems in dialogs, so tomorrow's should be better, but even today's should be usable for testing this bug.

Well unsure what was about exactly. 

Version: 7.6.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 8635c9aa8c6f1078a9e220076d5a08daf30077e8
CPU threads: 8; OS: Mac OS X 12.3.1; UI render: Skia/Metal; VCL: osx
Locale: nl-NL (nl_NL.UTF-8); UI: en-US
Calc: threaded

This is still relatively expensive
                  sw::DocumentTimerManager::DoIdleJobs(Timer*)
                   SwViewShell::LayoutIdle()
                    SwLayIdle::SwLayIdle(SwRootFrame*, SwViewShellImp*)
                     SwViewShell::ImplUnlockPaint(bool)
                      VirtualDevice::ImplSetOutputSizePixel(Size const&, bool, unsigned char*)
                       VirtualDevice::InnerImplSetOutputSizePixel(Size const&, bool, unsigned char*)
                        AquaSalVirtualDevice::SetSize(long, long)
                         CGLayerCreateWithContext
                          CGContextDelegateCreateForContext
                           ripc_GetLayer
                            RIPLayerCreate
                             _malloc_zone_calloc
                            ripc_Initialize
                            pthread_mutex_init

Incomplete stack
                  sw::DocumentTimerManager::DoIdleJobs(Timer*)
                   SwViewShell::LayoutIdle()
                    SwLayIdle::SwLayIdle(SwRootFrame*, SwViewShellImp*)
                     SwViewShell::ImplUnlockPaint(bool)
                      VirtualDevice::ImplSetOutputSizePixel(Size const&, bool, unsigned char*)
                       VirtualDevice::InnerImplSetOutputSizePixel(Size const&, bool, unsigned char*)
                        AquaSalVirtualDevice::SetSize(long, long)
                         CGLayerCreateWithContext
                          CGContextDelegateCreateForContext
                           ripc_GetLayer
                            RIPLayerCreate
                             _malloc_zone_calloc
                              szone_malloc_should_clear
                               large_malloc
                                _platform_bzero$VARIANT$Haswell


See also
https://www.pybloggers.com/2016/12/debugging-your-operating-system-a-lesson-in-memory-allocation/

Starting from
The key note here is that we can clearly see that we’re spending the bulk of our time in _platform_bzero$VARIANT$Haswell. This method is used to zero buffers. This means that macOS is zeroing out the buffers. Why?

@Patrick
Xcode instruments shows that cpu time being spend in _platform_bzero$VARIANT$Haswell in a regular fashion while typing. The link in comment 6 suggests this not being optimal. The question: is this worth investigating or should the bug be closed as NOTABUG or WONTFIX

Dear Telesto,

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