Huge performance slowdown when launching IronFox when used with uBlock

[lucasmz-dev]

Bug Description

Enabling uBlacklist (with a few lists) has a notable performance impact when launching IronFox on mobile.

Steps to Reproduce

1. Install uBlacklist
2. Reproducibility: Install lists: https://github.com/laylavish/uBlockOrigin-HUGE-AI-Blocklist, https://github.com/quenhus/uBlock-Origin-dev-filter, https://github.com/NotaInutilis/Super-SEO-Spam-Suppressor
3. Benchmark opening e.g. github.com with the extension enabled and disabled (close the browser between them, we're measuring the startup time)

Expected Behavior

Performance shouldn't be hurt that much

Actual Behavior

I've seen extra delays of 16/18 seconds.

Browser

IronFox 143.0.2

uBlacklist Version

9.2.0

Search Engine

DuckDuckGo

Additional Context

No response

Checklist

• I have searched existing discussions and issues to ensure this bug hasn't been reported before
• I have tried disabling other extensions to isolate the issue

[lucasmz-dev]

It seems to be an issue when used in conjuncture with uBlock, or something gets aggravated.
It goes from the usual 6 to 24 seconds with uBlack enabled. But without uBlock, it's even faster.

[ez-me]

I'm using Fennec (Firefox Nightly on Android) and by using large lists the memory usage on browser start can get to a gigabyte

I tried merging the lists and loading them from a single source, and the issue persists (fwiw, the merged file ended up being almost 10MB)

If I disabled all lists, memory usage and responsiveness improved significantly.

I also tried disabling uBo, but even by removing the lists there, or adding more, the difference was negligible.

[carterisonline]

I ran Firefox's profiler during startup and found that essentially all of this slowdown is spent running collectRuleset and the ruleset parser. My current workaround is disabling some larger rulesets. I'm going to spend some time looking into benchmarks and potential optimization here as uBo doesn't seem to have the same problem with similarly sized rulesets