benchmark_read_file.sh

#!/bin/zsh

function read1 {
    local i
    local FILE
    FILE=$(<$BFILE)
    for i in ${(f@)FILE}; do
        print $i
    done
}

function read2 {
    zmodload zsh/mapfile
    local i
    local -a FILE
    FILE=(${(f@)mapfile[$BFILE]})
    for i in ${FILE[@]}; do
        print $i
    done
}

function read3 {
    zmodload zsh/system
    local i
    local buff

    while sysread buff; do
        for i in ${(f)buff}; do
            print -- "$i"
        done
    done < $BFILE
}

function read4 {
    zmodload zsh/system
    local i
    local FILE
    FILE=$(<$BFILE)

    while sysread buff; do
        for i in ${(f)buff}; do
            print -- "$i"
        done
    done <<< $FILE
}

function read5 {
    local line
    while read line; do
        print $line
    done < $BFILE
}

BFILE="bench.txt"

: > $BFILE
integer fd
exec {fd}>>$BFILE

for i in {1..30000}; print -u $fd "lorem ipsum"

time (for i in {1..10}; read1 >/dev/null)
time (for i in {1..10}; read2 >/dev/null)
time (for i in {1..10}; read3 >/dev/null)
time (for i in {1..10}; read4 >/dev/null)
time (for i in {1..10}; read5 >/dev/null)

exec {fd}>&-; rm bench.txt