What is the bottleneck of the raspberry Pi4?

Hardware
1

Now that the new Pi4 is available, I assume the slow CPU is no longer the big bottleneck like it was the case for the Pi3.

Is the RAM important for the Raspberry? Of the 1Gb in the raspberry Pi3, I still have 400MB left. So I’m wondering if it makes sense to go for the 4GB version of the Pi4?

What about the Sdcard space? Currently, I’ve got a 16GB SD and use only 18% of space. In the Hassio documentation it is recommend to get at least a 32 GB SD card. Why exactly is this the case? I don’t see myself filling up even the 16GB card or is this more the case if you save video streams on your SD card?

2

the SD card is already a limitation, the pi4 should supposedly make it easier to use an external USB3 storage device for higher speed and reliability

3

More RAM is always better, linux caches in memory quite aggressively, the more ram the better.

The database file can get rather big, so drive space can be important.

However the advantage of a bigger card is more levelling and less likelihood of damage from repeat writes.