First time downloading bitcoin core and speed has dropped to 0.05%

So, I managed to get the Bitcoin Core to download the blockchain up to 87% overnight, but when I checked this morning, the speed just tanked. Now it's only increasing by 0.05% per hour. My laptop is unchanged, so what gives? I decided to install Bitcoin Core on an external HDD instead of setting the datadir to it. Could that be a factor in this slowdown?

Your node must have gotten to the point where it's now validating everything in the new blocks that it download from its peers after reaching its version's default "assumedvalid" block. But 0.05% per hour is tad too slow, are you using an HDD? If so, don't rely on the estimation too much since it's tend to underestimate the speed specially with slow disk and low dbcache. What are your settings and specs? The binary's directory doesn't affect your overall sync speed. What matters is if you've put the datadir in that external HDD as well, if so, that's also contributing to the issue.

Usually: lack of RAM. If it's <16 GB: add more RAM. Increase dbcache. If you put blocks on an external disk, at least keep chainstate on a local disk (SSD).

With HDD, I can imagine how you can quickly sync your Bitcoin Core full node from 0% to 87% within a day, overnight. It takes some days to sync your nodes to 87% and since Taproot, Ordinals BRC20 tokens in early months of 2023, there are more transactions in each block that can affect your synchronization progress. Increase your RAM, much cheaper to upgrade, then if possible upgrade your HDD to SSD. Ordinal Theory and the Rise of Bitcoin Inscriptions The emergence of Ordinals[url]

you wrote that you are using an external HDD this will be the issue. and as the other wrote before the first part of the core is going fast but to the end it slows down. I was also using an external HDD connected over USB and it was terrible then I tried NVMe disk and the full core was downloaded and validated in less than 20 hours.