[jrockway]

On a Raspberry Pi 3 with a random SD card I found laying around:

    pi@octopi:~ $ sudo hdparm -tT /dev/mmcblk0
    /dev/mmcblk0:
     Timing cached reads:   1366 MB in  2.00 seconds = 683.30 MB/sec
     Timing buffered disk reads:  62 MB in  3.02 seconds =  20.53 MB/sec

So it's going to take a couple seconds to page this thing into memory. (The memory speed isn't great either.) It's not so slow that I'd bother to write application software in C just to make startup 5 seconds faster, though.

Meanwhile on a Threadripper 3970x with SSD (but virtualized):

    $ sudo hdparm -tT /dev/sda
    /dev/sda:
     Timing cached reads:   20200 MB in  2.00 seconds = 10109.10 MB/sec
     Timing buffered disk reads: 5296 MB in  3.00 seconds = 1763.28 MB/sec