JSONL loading slow when using megawarcs

I'm trying to run [process_common_crawl_dump.py](https://github.com/huggingface/datatrove/blob/main/examples/process_common_crawl_dump.py) to dedupe an 80GB megawarc I have, and the jsonl loader is taking a long time to load the data. It appears to be single-threaded even if I set the number of workers higher.
What are the best practices for working with megawarcs? Should I extract the files in advance of running datatrove?

Start with examples/process_common_crawl_dump.py and trace how the JSONL loader handles an 80GB megawarc and worker settings. Reproduce the slow loading behavior with the reported command and compare it with extracted files if available. Done means documenting the supported megawarc workflow or identifying a concrete loading change, with evidence from the reproduction.

Written by the indexing model from the issue text.