As a user of both, I have a couple of salient observations.
Firstly, in respect of the O/P's basic complaint about the responsiveness of the Lr Develop Module, I don't have the same experience. Mine is pretty good. I find Lr responds to edit commands instantaneously as it always did since years ago. My computing environment is not even the most recent. I'm using a mid-2010 MacPro (desktop) with 24GB RAM, 2.66GHz clock speed and 24GB virtual RAM.
Regarding the quality of output from Lr, Martin Evening's comparison of the two applications, though a version or so predating the most recent for both applications, I think says it all, nicely laid out in a scientific, systematic manner. For those who haven't seen it, I can roughly sum it up as "6 of one, half a dozen of the other", though there are some nuances, so that rough statement doesn't do it complete justice. If you want the fine details read Martin's contribution. I've worked in both and always found that the toolsets in both applications allow one to derive approximately equivalent definition, tonality and colour, but I seldom work larger than for 13*19 inch output, so I haven't compared them for mural-sized enlargements.
There are four aspects of Capture One that don't often get picked up in these discussions:
(1) For those who own Phase One camera systems (I have an earlier one), for doing tethered capture this is the only option. Tethered capture comes in very handy in studio settings where absolute freedom from vibration is important. I'm using it for macro-photography just now and this is a clear case in point.
(2) There is a basic difference of architecture between C1 and Lr that I think is important, I have brought to Adobe's attention years ago, but it never worked its way into the Adobe way of structuring the application: when you do layered work with C1 (creating masks, etc.) you have at hand the full editing toolset. This is not the case for Lr, where any kind of masking (Adjustment brush or Graduated tool) offers only a reduced set of editing tools. I have long hoped for the day when Lr would allow one access to the full toolset when working on masked portions of the photo.
(3) When you use "Sessions" as the organizing principle for your work in C1, absolutely everything related to all the photos within that Session is self-contained within a file structure for that Session. So if you want to port the work you've done from one computer to another, all you need to do is send the Session over to C1 on the other computer and everything is identical between the two. Syncing has always been a nightmare with Lr.
(4) Finally, there are some Cultural Heritage specialty features in C1 designed for cultural heritage copy work with the latest Phase One and Digital Editions equipment that don't exist in Lr, but to access these you need the CH Edition of C1, which is terribly expensive.