Do not use full size words for low value variables (more if they are constant). Check here
Change strings in require to custom errors, saving gas on the way. The regex pattern is "\w*"\); and loop through the occurrences
Use unchecked { i++; } in loops where the end is known. The regex pattern is ; ?\w*\++. Save gas because solidity checks integers for over/underflow after 0.8.0 by default, so we can omit that because we know the limit