LSL is missing constructs that may reduce code a lot, save memory or increase performance.
Some are (not exhaustive yet):
  • break/continue in loops, possibly with break 2 and continue 2 for skipping to a higher loop
  • elseif
  • ternary operators a = b?a:d or shortcut, if possible: a = b?;d
A less obvious one but regarding memory usage a really big one: optionally using parameters by reference for function calls.