Interesting that you say that. After my previous FSX PC died, I bought a new PC and purchased P3D (v4.5). So this is basically a completely new installation of P3Dv4.5, plus add-ons. (Note that I re-purchased applicable add-ons where required to ensure they were P3Dv4 compatible -- it can be an expensive hobby).
As it stands right now, I am extremely happy with the performance I am getting on this newly installed P3Dv4.5 ... with no Hotfix. The Hotfix came out literally one week or so after I had completed my full reinstallation of the software and all the add-ons. But, with the performance I was getting, and upon reading that some people were having a few issues with the Hotfix and compatibilities with various add-ons, I figured I'd leave this new installation of the software alone (for now) due to the smoothness and the excellent, high frame rates I am experiencing ... albeit with the FPS slider set at "Unlimited".
For me, right now, at Unlimiited frame rates, P3Dv4.5, with no Hotfix, is the best (visually) and smoothest sim I have ever had on any PC I've ever owned. And the frame rates I'm getting are exceptional (80+ nearly all the time, with ORBX scenery and Active Sky -- dropping a little if I use, say, PMDG aircraft, and a bit more with the FSLabs A320). But, frames aside, it's all about smoothness ... and I am getting that in spades. I only see stutters if I set a limited frame rate. If I don't do that, she's exceptionally smooth, and the frames are great. So I leave it set to Unlimited. Set up this way, she appears, to me, to be "not broke". And, "if it aint broke, then don't stuff with it".
That said, I do plan to put the Hotfix on, eventually. I may very well see increased performance and benefit from setting a limited frame rate. All fair enough. But right now, all I want to do is fly. After all, it took me some 2-and-a-half months to get this new PC, purchase and install P3Dv4.5, research compatibility of add-ons, (re)buy and install those as required, configure cameras, and do everything else that needed to be done. It wasn't a small task. So, for now, I just want to have a bit of fun (flying). The Hotfix will come. I'm just not sure yet when I might go for it.