Karen just shared a video with me of Nightly on her N4. Fennec launches. Top sites load. For at least ten seconds after load, the screen responds to taps by flashing a grey highlight on top sites items, but won't load a page. Eventually, 18 seconds into the video, a tap results in a page load. This reminds me very much of Bug 936849. Please ask Karen for the video (or, Karen, let me know if I can host this in a public folder somewhere). This is a killer if this affects other users. The browser is totally unusable.

Behavior on Beta: https://dl.dropboxusercontent.com/u/3911373/Fennec/Video/Karen/Fennec%20beta%20on%20N4%20VID_20140121_143753_057.mp4 Behavior on Nightly: https://dl.dropboxusercontent.com/u/3911373/Fennec/Video/Karen/Fennec%20nightly%20on%20N4%20VID_20140121_143412_379.mp4

Similar with Bug 916968 or you mean something else?

I reproduced this exact bug on my N5 using today's (Jan 23) Nightly. I also saw something similar when starting the freshly-updated Nightly - the browser opened with the "About Nightly" page open, as expected but the page was blank and there was no progress bar or anything happening for a good 4-5 seconds. Felt like a similar amount of time as the top-sites-to-respond issue.

(In reply to Ioana Chiorean from comment #2) > Similar with Bug 916968 or you mean something else? I don't believe it's the same: we're not loading web content.

Using my LG Nexus 4 (Android 4.4.2) akin to the video, I was only able to reproduce behavior similar to the Nightly video (with hefty profiles) only with AdBlock Plus installed. In-fact, with AdBlock Plus installed, there seems to be a lengthy period before Gecko becomes respondent on start-up. Does Karen have that installed? On Beta with AdBlock Plus installed, I am not seeing the same delay.

(In reply to Aaron Train [:aaronmt] from comment #5) > Using my LG Nexus 4 (Android 4.4.2) akin to the video, I was only able to > reproduce behavior similar to the Nightly video (with hefty profiles) only > with AdBlock Plus installed. Bug 795436?

Aaron, your sleuthing does amaze me. OK, here is what happens. If I just disable it, still the insane lag. I have to uninstall it completely for it to have any positive effect. But even after uninstalling it, there is still a lag - just not as severely pronounced. So definitely better, but I an tapping three thumbnails before it kicks in (which is certainly better than the 15 or so furious taps I pounded the phone previously)

(In reply to Karen Rudnitski [:kar] from comment #7) > Aaron, your sleuthing does amaze me. > > OK, here is what happens. If I just disable it, still the insane lag. I have > to uninstall it completely for it to have any positive effect. That raises the terrifying prospect of "disabling add-on doesn't work". Is that true even if you disable it, then force-close Fennec? > But even after uninstalling it, there is still a lag - just not as severely > pronounced. So definitely better, but I an tapping three thumbnails before > it kicks in (which is certainly better than the 15 or so furious taps I > pounded the phone previously) Perhaps two causes, then. How many add-ons do you have installed? It sounds like we should respond to taps on Top Sites by opening a blank page until Gecko's ready to populate it…

I did force close, for the record. It was my only add-on. Nothing else installed.

I'm impressed that two slow startup bugs become active on the same day (or within days) of each other, both related to AdblockPlus. Perhaps fate is trying to tell us something.... Looking at AMO, there are ~226K daily users of AdblockPlus on Firefox for Android (Fx26) https://addons.mozilla.org/en-US/android/addon/adblock-plus/statistics/usage/applications/?last=30 (Look at app named 'aa3c5121-dab2-40e2-81ca-7ea25febc110' in the chart. Tap the other 'Firefox' names in the legend to hide them.)

What if anything is planned for 29 here to warrant tracking?

(In reply to Aaron Train [:aaronmt] from comment #11) > What if anything is planned for 29 here to warrant tracking? Further investigation, I imagine.

Marking as dup as there's already bug about slowness related to add-ons (namely, AdBlock+).

Removing regressionwindow-wanted flag since the bug is marked as duplicate.