build.sh file performance issue

Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead
if [ ! -f "$PACKAGES_CONFIG_MD5" ] || [ "$( cat "$PACKAGES_CONFIG_MD5" | sed 's/\r$//' )" != "$( $MD5_EXE "$PA...

cat is a tool for con"cat"enating files. Reading a single file as input to a program is considered a Useless Use Of Cat (UUOC).
It's more efficient and less roundabout to simply use redirection. This is especially true for programs that can benefit from seek-able input, like tail or tar.
Many tools also accept optional filenames, e.g. grep -q foo file instead of cat file | grep -q foo.
Example of incorrect code:

cat file | tr ' ' _ | nl
cat file | while IFS= read -r i; do echo "${i%?}"; done

Example of correct code:

< file tr ' ' _ | nl  
while IFS= read -r i; do echo "${i%?}"; done < file

The build.sh mentioned is located at

resources/build.sh

Line 70 in 3c21547

    
           if [ ! -f "$PACKAGES_CONFIG_MD5" ] || [ "$( cat "$PACKAGES_CONFIG_MD5" | sed 's/\r$//' )" != "$( $MD5_EXE "$PACKAGES_CONFIG" | awk '{ print $1 }' )" ]; then

Which is where you can send PR against.