[mark_undoio]

I helped implement fast conditional breakpoints in UDB (time travel debugger for Linux) - https://www.youtube.com/watch?v=gcHcGeeJHSA

We used GDB's conditional breakpoint bytecode https://sourceware.org/gdb/onlinedocs/gdb/General-Bytecode-D... to get a speedup in the thousands of times vs plain conditional breakpoints.

That works for us because we've got in-process agent code that can evaluate the breakpoint condition without trapping. It should be possible to do this in other debuggers with a bit of work, though we have the advantage of in-process virtualisation to help hide this computation from the process.