If one remote works fine and the other doesn’t, it’s not the core. I have an old iPad 4 that works fine, but it literally has nothing else installed on it. I have an older iPad Pro (1st gen) that works ok but can get sluggish and crashes (usually right after app launch) sometimes. And then I have an iPhone 12 that is pretty terrible - sluggish, crashes, stutters - but I use it more than any other remote because it’s just so convenient.
There are a lot of threads on issues that folks have. The one specifically on stuttering is worth looking at.
I think the philosophy many if not most users have is that either Roon’s good features are worth the pain (I’m in this camp) or they are not (it is surprising how many people on this forum say they are in the latter group, but keep right on using it nonetheless). I can’t tell you what to do… but my suggestion if you do like some of the features enough to keep going, is not to get involved in the complaining here. There are a lot of things that suck. I hope they’ll get fixed. But in the meantime I deal with them because for me content, exploration, combination of local content plus streaming, and occasional up sampling all make the juice worth the squeeze. And when I get frustrated, I spin records for a while.
Good luck!