On rhel9, this is a list of my installed shells. You might notice that dash is smaller than ls (and the rest of the shells).

  $ ll /bin/bash /bin/dash /bin/ksh93 /bin/ls /bin/mksh
  -rwxr-xr-x. 1 root root 1389064 May  1 00:59 /bin/bash
  -rwxr-xr-x. 1 root root  128608 May  9  2023 /bin/dash
  -rwxr-xr-x. 1 root root 1414912 Apr  9 07:26 /bin/ksh93
  -rwxr-xr-x. 1 root root  140920 Apr  8 08:20 /bin/ls
  -rwxr-xr-x. 1 root root  325208 Jan  9  2022 /bin/mksh

  $ rpm -qi dash | tail -4
  Description :
  DASH is a POSIX-compliant implementation of /bin/sh that aims to be as small as
  possible. It does this without sacrificing speed where possible. In fact, it is
  significantly faster than bash (the GNU Bourne-Again SHell) for most tasks.

It is much simpler (and therefore less resource-hungry) than bash.