Devtools slow and occasionally unresponsive on some sites

(Julian Descottes) #41

| 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

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 :confused: . 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.

(Adin) #43

Hi, I’ll check out the Nightly .
I’d rather not have the contents of “devtools.debugger.pending-breakpoints” on a website. Can I send it to you privately?

(Guirec Corbel) #44

I still have the issue with Firefox 59. A single tab opened with the debugger take 5Go of RAM.

(Guirec Corbel) #45

I just created this bug report :

(Guirec Corbel) #46


Jason Laster did a huge job to improve perf and it’s a lot better with Firefox 60a1, the current nightly build.

You can visit this repo if you want more about the debugger.