Why do I see diminishing returns on speed of backgrounding processes in Bash?

Question

I'm trying to figure out why I'm seeing diminishing speed returns when backgrounding lots of processes in a Bash script. Something like:

function lolecho() {
    echo "lol" &> /dev/null
}
c=0
while true; do
    for i in $(seq 1 1000); do
        lolecho &
        ((c+=1))
        if [[ $((c%1000)) -eq 0 ]]; then
            echo "Count $c"
        fi
    done
    sleep .1
done

It screams out of the gate up to 10,000, 20,0000... but it then starts to slow down in how quickly it can put up backgrounded processes around 70,000... 80,0000. As in, the rate at which the count prints to screen slows down by a seemingly linear amount, depending on the total.

Should not the rate at which the machine can run background jobs that finish basically instantly be consistent, regardless of how many have been added and closed?

Answer 1

The answer was to use the Linux built-in wait command:

function lolecho() {
    echo "lol" &> /dev/null
}
c=0
while true; do
    for i in $(seq 1 1000); do
        lolecho &
        ((c+=1))
        if [[ $((c%1000)) -eq 0 ]]; then
            echo "Count $c"
        fi
    done
    wait   # <------------
done

The script now produces processes consistently and faster in general.