| Any news on this front […] Using FF 57.0.3
Stepping (F10) performance has been improved on 59 already. “Opening the debugger” can be slow for various reasons, we are still working on improvements related to sourcemaps. If you have a link with steps to reproduce your issue, the best is to open a ticket on https://github.com/devtools-html/debugger.html/issues
Always worth trying Nightly, as we have been landing several performance improvements to the debugger in Firefox 59.
| I have another issue where a bunch of breakpoints keep coming back
| no matter how many times I remove them.
I thought most “breakpoints” issues were fixed before 57 . As a workaround you should be able to go to about:config and look for “devtools.debugger.pending-breakpoints”. Could you copy the value and report it here? After that you can right click and “Reset” the value. Hopefully it should remove those persistent breakpoints.