Folks,
Not sure when this started, but I cannot edit correctly on my dashboard.
It happens several places, but clicking edit and then on the schedule-card item enters the editing dialogue. However, going deeper, like pressing on a schedule, just hangs the process completely, using 100% CPU from the safari webkit process.
Rather useless 
Dweeb
Hi, welcome to the forum!
I guess you mean logging in from a webbrowser on MacOS and your HA runs on another system, right?
If so, have you tried accessing HA from another system?
There is a bug in Safari that Apple has not addressed that can cause the HA GUI to basically not respond. Use any other browser (including other webkit browsers), and it's not an issue. So I'd at least try another browser to see if that's your issue.
Should be something different... Safari issue (BTW, I believe fixed now with Tahoe 26.4.1) wasn't causing 100% CPU consumption, it was just hanging on load/reload of some specific webpages, HA being one of these. Anyhow solution was relatively easy, use mDNS to connect to HA (e.g. http://homeassistal.local:8123) or true FQDN, if available (e.g. when HA was exposed directly to Internet). So easy to rule this out with this test.
I am on macOS (see title) and that's the limit.
There is an app that I use (I assume it uses WebKit) and the connection is via http://192.168.1.113:8123 which is the direct address to the Rasberry Pi.
I have been forced to upgrade my phone, so I have a 17Pro latest and no so greatest.
It hangs there too.
Edit: It hangs the iOS phone app.
Edit: I tried the direct IP address and port from Brave browser. The result is that the browser uses 100% of a CPU for the "Brave browser Helper (Renderer)"
FWIW. As someone mentioned the possibility of the webkit code having been repaired in Tahoe, I upgraded to macOS 15.7.7 in the hope that this "fix" might have been backported.
Alas, the thing still hangs on the schedule-card.
The bad news is I really need to change the scheduling!
What about Chrome? The problem is that many browsers are really the same code under the hood, just with different user-facing style and branding. WebKit makes it easy
One solution is to download the Home Assistant iOS app and not use a browser.
As I wrote. I have tried
a) macOS App
b) macOS Brave (Chrome based) browser
c) macOS Safari browser
d) iOS Safari browser
All appear to have the same issue