Last updated blocklist.xml from <=2021-10-19 causes noticeable additional v2021.09+ start CPU time

[walmar]

At last more than 8s with an AMD A10-6700 APU from 2013.

I have observed the behavior by trial-and-error method.

• When I restarted Waterfox several times after
  • replacing profile files
  • installing various builds
  • inspecting backups

The behavior can be reproduced by

1. checking the blocklist.xml file creation date of an actively used profile
2. starting Waterfox with a freshly created profile and viewing the CPU time of waterfox.exe process (with the highest) in Windows Task-Manager
3. closing Waterfox and viewing the CPU time again after replacing the blocklist.xml file with that from esr68 branch of the gecko-dev repository (created in 2020, 628 KB size) for comparison

The slower start of Waterfox has been also mentioned by other users in the past, while it could not be reproduced by the contributer @hawkeye116477.

• J on Waterfox Classic 2021.10 Release - Internet Archive

  All previous versions of WF Classic load instantly, upgrade to 2021.09 and it takes about 5 seconds to start

• @Rikk commented on Newer versions are slower compared to 2021.08.1 with certain websites · Issue #50 · WaterfoxCo/Waterfox-Classic · GitHub

  Worth of mention, also starting at that version, browser takes much much longer to start (high cpu for a while before truly loading as before).

The MozillaZine Knowledge Base describes the blocklist.xml.

contains a list of add-ons that Mozilla considers to be harmful to the user (contains security vulnerabilities, adversely affects browsing experience, etc.)

is by default automatically downloaded once a day from mozilla.com

Deleting blocklist.xml will clear the block list until the file is redownloaded.

This are my settings:

• extensions.blocklist.detailsURL;https://blocked.cdn.mozilla.net/
• extensions.blocklist.enabled;true
• extensions.blocklist.interval;86400
• extensions.blocklist.itemURL;https://blocked.cdn.mozilla.net/%blockID%.html
• extensions.blocklist.level;2
• extensions.blocklist.pingCountTotal;3254
• extensions.blocklist.pingCountVersion;158
• extensions.blocklist.url;https://blocklists.settings.services.mozilla.com/v1/blocklist/3/%APP_ID%/%APP_VERSION%/

  Conclusions

  Based on the above mentioned, my conclusions are that

• after 2021-10-19 the blocklist.xml file is not automatically downloaded once a day from mozilla.com, the day before I updated from the build 2021.09 to 2021.10 and further
  • before the date, the file has grown between 2019 and 2021 to 998 KB size according to the backups
• an already automatically downloaded blocklist.xml file causes noticeable additional start CPU time since build 2021.09
  • If it is replaced by the default file (which is from 2017 and is 253 KB in size), the CPU needs as long as before the occurrence of the error
  • unidentified changes from build 2021.09 seem to cause the longer start time

[Quisquose]

@walmar Thank you for this.

I have been enduring the same excruciatingly slow launch problem for months, but I didn't know what what causing it. However, replacing blocklist.xml, as you suggested, has made a huge difference.

Version 2021.07 was the last version that opened at normal speed for me (2.3 seconds with 15 extensions). Any version after that (up to and including v2022.08) caused my Waterfox launch speed to drop from 2.3 seconds to 17 seconds.

I would have stayed on v2021.07, but sites like Reddit are completely unusable for me on that version (posts won't load and the browser starts freaking out).

Replacing blocklist.xml got my launch speed down from 17 seconds to ~3.5 seconds (not as fast as before, but a massive improvement) so the latest versions are now much more usable for me.