@willcroft @jensimmons @nicolas17 I’ve added reproduction steps to FB20414621.
I can 100% reliably cause Safari 26.0.1 on macOS 15.7 to slow down and eventually close by repeatedly typing and backspacing in the address bar.
Even once I stop typing and it eventually goes back to 0% CPU, the whole browser is then sluggish when doing things like clicking into the address bar or maximising the window. Continuing to type/backspace causes it to lock up and close.