Then you should take a look at this to get started.

See also Qt::AA_EnableHighDpiScaling in Qt's Application Attributes enumeration

When are you setting that attribute ?

@jcelerier said in Rendering performance problems on iMac with Retina 5K:

https://bugreports.qt.io/browse/QTBUG-61384?focusedCommentId=361794&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-361794
.

That one.

@fxxxx you should set attribute for your main window: setAttribute(Qt::WA_NativeWindow); but it causes optimization problems, because it is legacy feature. anyway, it will solve your problem, and windowHandle() should return valid pointer, and will emit signal screenChanged().