Raspberry Pi's are atrocious at SD IO, the Pi 4 made a big improvement, but it is still bad, especially if you don't use a Samsung EVO+ (the best performing SD card by a long shot on a Raspberry Pi).
But anything serious I'd highly recommend just using an SSD drive, you can get one for about $30 and be 100x faster.
Some tests I did. Using something other than a Samsung EVO+ would have been much worse.
Maximum performance out of the Raspberry Pi 4 with an SSD drive
I'm planning to run the jussi for my API node on a Raspberry Pi 4 with 4Gb RAM and SD card.
Is this sufficient in your view or should I add a SSD on USB?
I have both the cable and SSD drive but understood jussi just used RAM for cache and didn't really do IO.
It will mostly be cpu/ram so I don't see a huge difference /w SD vs SSD outside of management time (and reliability on power outages as SD corrupt easier).
You can get a 250G SSD and cable for around $40.