Will performance improvements and optimizations help with older PCs, so people won't have to spend more out of pocket to be up to par?
TL;DRYes, the code optimizations aren't specific to machine specs, so they should help both low-end and high-end PCs (and servers), though exact savings per machine type are hard to judge.
Yes. We'd like to make it clear that all the optimizations we're doing code-wise, they're not specific to any particular machine specs. The code doesn't really care whether it's a high-end or low-end machine that it's running on. If we're putting optimizations in where we found something we don't need to update, this object in this situation, or we cut down amounts of expensive code that we call, those kinds of fixes will apply to both low end and high end. So I think it's probably hard to judge exactly how much on a high end versus a low end you save, but the code is fixed for both, so you should see a saving in both. The aim is to optimize across the board.
It kind of applies for servers as well, because obviously they're super high-end PCs, if you want to think of them that way, so any optimizations we do will benefit the servers as well as clients. Triple win.