Improving a Glock 23? Hmmmmm...
Well first, I'd replace that flimsy lil stamped slide stop with a hefty cast model just like on a 1911. I'm sure you'll see a marked improvement in engagement, resulting in faster reloads.
Now, I'm bettin' that you might have trouble fitting the new part to your Glock as-is, so I'd recommend that you go ahead and replace the frame with one that'll readily fit the slide stop. I wouldn't be at all surprised that it'll feel better in your hands, to boot.
Of course, it's likely to be a serious problem getting your existing Glock slide to fit the new frame rails. I'd go ahead and buy a slide that's natively compatible with the frame, rather than suffer the expense and headaches of such extensive gunsmithing. While you're at it, you might as well head off potential cycling issues by replacing the barrel, recoil spring, guide rod, and any other hardware required by the new slide for smooth operation.
After all this, you're almost home free...just a few more minor accessories and your dream pistol is complete. Things like magazines, sights, and your choice of something you could only dream of before...grip panels.
By now, you might be a little concerned that your Glock 23 has gotten a bit heavier. Don't worry. Now it's slimmer, more ergonomic, and it'll point every bit as nicely...maybe even better, depending on your hands. Also don't overlook the fact that your Glock 23 is now beautiful. The guys at the range may even compliment you on how nice your "1911" is. Now, I know that this rankles some Glock guys but don't let it get to you. Just nod and smile in the secret satisfaction that your shooting one helluva highly customized Glock 23. They'll be none the wiser.