Looking to increase the speed of my bash script

The title pretty much says it all, I have a short bash script that processes gigs and gigs of data. I am looking for any improvements to make it faster. This is my very first bash script so please be gentle ;) I am really only concerned about the while loop, the rest of it is fine I think, its the while loop where the real work is done and could use the most enhancement.

#!/bin/bash

# This script will clean a WPA wordlist
# It will read every line of the given file
#       Remove all whitespace except for newlines
#       Delete the line if it is less than 8 chars or greater than 63
# It will then exit with time of execution


IFS=$'\n'       # make newlines the only separator



startTime=$(date)       # start time of execution
fileToClean=$1          # this is the file we will be sanatizing, 1st cmd line arg
deletedlines=0          # number of lines that did not meet WPA PSK critera
validlines=0            # number of lines that were valid PSKs  and added to file


if [ -z $fileToClean ]; then #No file specified
        echo ""
        echo "No file specified!"
        echo ""
        exit -1
fi

if [ ! -f $fileToClean ]; then #File does not exist
        echo ""
        echo "File not found!"
        echo ""
        exit  -1
fi

#By this point I am assuming I entered a valid file and will begin cleaning
echo ""
echo 'Cleaning word list: ' $1
echo "Start Time: " $startTime
echo ""


    while read line; do  #read every line in file and save to var line

            trimmedline=$(echo $line | xargs -0)  # use the xargs command to trim
                                                  # white space and save trimmed line
                                                  # into the new var trimmedline

            if [ ${#trimmedline} -ge 8 ] && [ ${#trimmedline} -le 63 ]; then     # if trimmedline length >= 8 && <= 63
                    echo  $trimmedline >> $outputfile
                    ((validlines++))
                    continue
            fi

            ((deletedlines++))


    done <$fileToClean


utime="$( TIMEFORMAT='%lU';time ( ls ) 2>&1 1>/dev/null )"  # this stores the executio time in the var utime

echo "Processing completed, it took" $utime "and $deletedlines were deleted."
echo $validlines "were added to the output file "$outputfile" as they were valid PSKs"
echo ""