Every few minutes, Bitcoin Core is unresponsive for a few minutes, most likely because of the large wallet combined with a lack of processing power. It's not very nice to work with, and consumes 1 full CPU core.
That's interesting, I thought Bitcoin Core would be more efficient and effortlessly check new transactions in both mempool and new blocks for the addresses in the wallet with some fast search structure.
Those servers run by hackers who snatch coins that are sent to known private keys must have databases of many millions of addresses, I wonder if they run custom code that is much faster than Core because of its more narrow purpose.