Same problem (or similar) on an M2 Pro here (Sequoia 15.4). Interestingly, the system doesn't freeze immediately; after I start dtrace I can switch windows, interact some with the browser, type things. But gradually each piece of the system freezes up and won't respond to anything. It feels like it's anytime something tries to fork a new process, it freezes. The clearest example is that typing a command in iTerm and hitting enter causes iTerm to freeze. Trying to launch something with Spotlight or the Dock or Quicksilver causes those components to freeze. Eventually everything is wedged enough that I have to hard-reboot. Does that match what you see, @zjz ?