I use goodreads as well and find the UI/UX very old fashioned. The lag is astonishing as well. What are some issues you have with it?
As much as possible, I find myself interacting with Goodreads through calibre plugins; I've got a library with zero actual book files that contains an entry for every book in my library, and I mainly use that to browse my collection. Since syncing that list takes so long, my actual calibre libraries are also synced to Goodreads, as that's where I actually make my changes.
With Library thing's recent removal of library limits, I'm thinking more and more about abandoning Goodreads--except I don't know if there's a calibre plugin for PT, and I've spent so much time adding and updating book records for items in my goodreads library, which would have to be redone for LT.
Amazon should never have been allowed to buy Goodreads.
This is why big social media sites have such high valuations. Any small group could develop an alternative to Facebook. However, the chances of that usurping them is almost zero. The same goes for Goodreads.