Well, if the file sizes are too big you need to reencode them. That's just how it is, regardless of the software you're using. If your computer is too slow at that, you may want to use faster settings. For example, you could use a codec that's hardware accelerated by your GPU.

You can link the makeMKV libs to handbrake so it's a one step process disk -> compressed form.

#!/bin/bash

# Intention: replace aacs decoding with makemkv's superior libmmbd programatically

# elevate privilages to sudo
[ "$UID" -eq 0 ] || exec sudo bash "$0" "$@"

# test if libmmbd is installed already, exit otherwise
libmmbdpath=$(find /usr -name libmmbd.so.0)
echo "libmmbd path is $libmmbdpath"
if [[ ! $libmmbdpath == *"/lib/"* ]]; then
    echo "libmmbd not found, please install makemkv first"
    exit 0
fi

# test if libaacs is installed already, set desired path otherwise
libaacspath=$(find /usr -name libaacs.so.0)
echo "libaacs path is $libaacspath"
if [[ ! $libaacspath == *"/lib/"* ]]; then
    libaacspath="/usr/lib/libaacs.so.0"
else
    echo "libaacs found, you must uninstall libaacs"
    exit 0
fi

# test if libbdplus is installed already, set desired path otherwise
libbdpluspath=$(find /usr -name libbdplus.so.0)
echo "libbdplus path is $libbdpluspath"
if [[ ! $libbdpluspath == *"/lib/"* ]]; then
    libbdpluspath="/usr/lib/libbdplus.so.0"
else
    echo "libbdplus found, you must uninstall libbdplus"
    exit 0
fi

# if we made it here, it's time to take action

# softlink mmbd to aacs
ln -s $libmmbdpath $libaacspath

# softlink mmbd to bdplus
ln -s $libmmbdpath $libbdpluspath

echo "successfully set up libmmbd as the system decrypter"
exit 0