Latest Camera Raw 12.4 proved itself to be sluggish. Be cursed the day that I updated it! ))
But most amazing is that it is freezing not on some action, but on simple mouse movement passing over the image that is being cropped. Looks they have some 'forced redraw' issues with that.
My firstname.lastname@example.orgGz with 32Gb RAM can handle very complex tasks quite fast -- proved by previous versions of Photoshop (2015.5.3) or 3DStudio or Adobe Premiere... but passing a mouse over image seems to be a very, very hard and resource consuming task.
Also to blame - because of this lags and delays I accidently pressed 'Open as copy' instead of 'Open'. And -- ooops! all my work for several hours had gone with the wind. No adjustments or brush work was saved to XMP files.
First, actions are being taken (there is processing as you can see, the RGB values are updated as you move the mouse).
2nd, as this is a user to user forum, and Adobe isn't here to assist, you may not get anything out of all this as we can't diagnose the software code, it could be your GPU (try turning it off, updating the driver).
3rd, "Acronis True Image Protection" creates a problem for ACR so if you're running it, disable it.
4th, yes you accidently pressed 'Open as copy' instead of 'Open' and now you know not to do so as this design differs from Open of course.
Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
1st) Updating the histogram should not take 99% CPU, that's quite simple and never required this many resources.
2nd) Adobe may not reply officially, but if they ever need any feedback, they will surely come and read this.
3rd) I don't have this software installedm that's not the case.
4th) That's not my fault, it's a bad UX design - or you may call it a 'design bug'.
Let me explain and show you the video:
Menu pops-under when you click 'Open' and you accidently choose 'Open as copy' instead. The default menu point should be "Open" of course. Or maybe the menu should be positioned a bit left, not right under the cursor.
And 'Open as a copy' is behaving unpredictale -- while 'Open' keeps your adjustments in XMP file, 'Open as a copy' does not. That means you will loose all your corrections, including brush work and fine adjustments.