Here's an article describing Califonia's issues, but it's from November 10.
https://thehill.com/homenews/campaign/416080-why-california-counts-its-ballots-so-slowly
It describes a whole lot of things California does to allow more voters to vote, so that's a good thing, and I agree with the general statement in the article that it's better to be correct than to be fast. However, it seems to me that it ought to be possible to be both, at least when "fast" would mean "a week or less".
Reading the article, it looks like the biggest bottleneck may be their signature verification process. Apparently, in California, it requires a "high level administrator" to throw out a ballot for a signature mismatch. It doesn't give more detail except to say, "in California, several more layers of increasingly senior officials inspect a ballot, in an effort to count as many as possible."
There's no other details, including who these "increasingly senior officials" actually are. However, I'm picturing people who have jobs to do still having a huge stack of votes that have to be viewed personally.
If the quarter million remaining votes are all of that sort, the situation isn't absolutely horrible. If they are concentrated in certain areas, i.e. if there are precincts that simply haven't been run through the counters yet, it would mean local races where the people running still don't have a clue who won three weeks later.
So, California needs to look at the process and see if there are ways to speed it up. It isn't good to have this kind of delay. Also, it can't just be California. If there are 2 million outstanding votes, and California has a quarter million, someplace else is also in trouble.
Anyway, I want to make sure no one thinks that I'm implying something nefarious is going on. I just think it's kind of crazy that there's still something between 1 and 2 percent of the total votes that have yet to be counted. Hopefully it's a one time glitch when people didn't really understand how different this year was going to be, and how procedures that were written for processing a few thousand absentee ballots suddenly had to be used to process a few million ballots.
ETA: The article would also explain why the 4x the votes and 4x the counters wouldn't work under California laws. You can't suddenly add 4x the "high level administrators". If the law requires specific people in California to be involved in the process, you can't create more of them to meet higher levels of demand.
