Unfortunately, faster doesn’t automatically beat known quantity.

People will keep opening the old thing because it’s in their bookmarks, it matches their muscle memory, and if something goes sideways they can say “I used the normal tool.” That last bit matters more than we’d like. Nobody wants to be the person explaining why they used Steve’s Fancy Speed Button and now accounting is looking at them funny.

I’d stop treating it like a performance issue and treat it like an adoption issue. Sit with a couple people and watch them do the workflow in the old UI. Don’t pitch yours yet, just watch. There’s usually some tiny stupid thing hiding in there like an export format, field name, filter, approval step, or “I need this screenshot for Carol” that your faster tool doesn’t do yet.

Once you find that, make the new path feel boringly safe. Same words, same outputs, same permissions, same place they already go if you can swing it. Redirect the old URL if that’s politically allowed. Get one respected power user using it and let them be the unpaid marketing department.

Also maybe add just a pinch of telemetry/logging if you haven’t already. Not creepy, but just enough to see who tries it, where they bail, and what they still go back to the old UI for.

I bet you didn’t build a bad tool. You built a faster hallway and everyone is still walking through the old door because the old door has snacks and fun reruns of their favorite episodes.