I've gotten used to it taking a dozen seconds to load on DEBUG builds, but now it just doesn't work.

This adversely affects the time it takes to debug things.

I just checked with the latest inbound with --enable-debug and --disable-optimize, and I'm not seeing anything like a dozen seconds or it not loading (maybe a couple of seconds when opening a new toolbox). I tested on OSX and a linux VM and see similar results. Can you confirm that you see this issue on a clean profile? If so, are there any other relevant build options I can try to reproduce with? And, are you loading the Browser Console or the web console in the toolbox for a page?

I take back my 'couple of seconds' comments. I was running an artifact debug build - when I do a full build it's definitely slower. Still not able to reproduce dozens of seconds / it not working at all so going to leave the needinfo out to hopefully track this down.

I believe it's due to the hundreds of messages in the console of some of the webpages I'm trying to diagnose. Are we trying to load the entire console's log when we initialize it?

(In reply to Jeff Gilbert [:jgilbert] from comment #4) > I believe it's due to the hundreds of messages in the console of some of the > webpages I'm trying to diagnose. Are we trying to load the entire console's > log when we initialize it? It does print all cached messages when the console is opened. There's a bug with some patches attached (which needs to get finished up) that makes this smarter by only rendering messages that are within the viewport (Bug 1308216). In the meantime, is there a particular page that you are seeing this issue on so I can test it?

Here's an example page: https://www.khronos.org/registry/webgl/sdk/tests/deqp/functional/gles3/lifetime.html?webglVersion=2&quiet=0 Particular waiting for it to finish ("TEST COMPLETE" at the bottom of the page), and /then/ opening the web console.

Marking as dependent on the perf work for the new frontend in Bug 1308216

I hope that the solution in Bug 1308216 will bring the new frontend at least to parity with the current one, and I'd expect an improvement. In the meantime if this is blocking you here are a couple of options: 1) change the devtools.hud.loglimit pref. It defaults to 1000 but if you set it to be lower then after 100 messages old ones will be pruned off. Setting it to 100 or so will mean you can't look back as far but it should be significantly faster to open. 2) if switching the limit isn't acceptable in your case, you can flip back to the old frontend with this pref: devtools.webconsole.new-frontend-enabled.