It's going to be long, but $ReplacExCS() is VERY FAST. Faster than $SortTok() or your $RegSubEx().
$replacexcs(%s,A,a,a,A,B,b,b,B,C,c,c,C,D,d,d,D,E,e,e,E,F,f,f,F,G,g,g,G,H,h,h,H,I,i,i,I,J,j,j,J,K,k,k,K,L,l,l,L,M,m,m,M,N,n,n,N,O,o,o,O,P,p,p,P,Q,q,q,Q,R,r,r,R,S,s,s,S,T,t,t,T,U,u,u,U,V,v,v,V,W,w,w,W,X,x,x,X,Y,y,y,Y,Z,z,z,Z)
