Make sure you set Dropout Protection to minimum in Studio One, it causes more problems than it helps. And yes, sus pedal set to ECO is definitely the way to go for composing and HQ+ for mixdown.
Sorry to hear of your problems - that's very frustrating. From what I've read in various forums, it seems that the Walker D behaves better on Mac computers. I run the full 36 velocity patch with 2 mic sets (Hammer & Room) in Logic X Pro on an old 2009/2010 Mac Pro 2.8Ghz Quad core with 20GB ram without any problems or drop outs, and that is with dense playing & pedalling.Yeah, I tried with 2000 max voice count - no effect and Kontakt reports only like 100-200 voices running. It could be Windows-only thing but I've done pretty much all latency etc tunings available (C states, hyper-threading etc.). To me it seems like there is some kind of pedaling bug in Walker which keeps cumulating CPU load over time.
Good point about Mac - I also have a i5 Mac Mini available to test this on if I go through the trouble of installing it there. Maybe worth a shot even if it wouldn't be possible to start using all the other stuff on that tiny Mac. Thanks!