Linux – How to find files within a size range

$> find . -size 0 | while read f; do rm "${f%.*}."* ; done

explanation:

1. find all files with size 0
2. pipe the names to the while loop
3. cut of the suffix (extension) part ${f%.*} (read man bash)
4. rm all other files with the same base

The fastest I can come up with is to use xargs to share the load:

find . -type f -print0  | xargs -0 grep -Fil "mypattern" 

Running some benchmarks on a directory containing 3631 files:

$ time find . -type f -exec grep -l -i "mystring" {} 2>/dev/null \;

real    0m15.012s
user    0m4.876s
sys     0m1.876s

$ time find . -type f -exec grep -Fli "mystring" {} 2>/dev/null \;

real    0m13.982s
user    0m4.328s
sys     0m1.592s


$ time find . -type f -print0  | xargs -0 grep -Fil "mystring" >/dev/null 

real    0m3.565s
user    0m3.508s
sys     0m0.052s

Your other options would be to streamline either by limiting the file list using find:

   -executable
          Matches files which are executable and  direc‐
          tories  which  are  searchable (in a file name
          resolution sense).  
   -writable
          Matches files which are writable.             

   -mtime n
          File's  data was last modified n*24 hours ago.
          See the comments for -atime to understand  how
          rounding  affects  the  interpretation of file
          modification times.
   -group gname
          File  belongs to group gname (numeric group ID
          allowed).
   -perm /mode
          Any  of  the  permission bits mode are set for
          the file.  Symbolic modes are accepted in this
          form.  You must specify `u', `g' or `o' if you
          use a symbolic mode. 
   -size n[cwbkMG]  <-- you can set a minimum or maximum size
          File uses n units  of  space.  

Or by tweaking grep:

You are already using grep's -l option which cause the file name to be printed and, more importantly, stops at the first match:

   -l, --files-with-matches
       Suppress normal output; instead print the name of each input file  from
       which  output would normally have been printed.  The scanning will stop
       on the first match.  (-l is specified by POSIX.)

The only other thing I can think of to speed things up would be to make sure your pattern is not interpreted as a regex (as suggested by @suspectus) by using the -F option.