I'm not going to comment on RS.com's commitment or there goals for Railworks in the future or the DLCs they bring out as I'm fine with that as it is.
In regards to performance, Railworks isn't obviously the best preforming Simulator which most of us can agree on and in some cases it can have quite a few hickups, it is a somewhat borrowed code base stretching back many years and one can see that with the inclusion of Kuju related files and so forth. The underlining issue, and not trying to be so negative is that while Railworks is a pretty good simulator it is crippled on old technology in some aspects, for example it does ultilise multiple cores and physisX isn't on the graphics card which is technically where it should be nowadays. Before anyone mentions, yes those are to be included in a revamp later this year which doesn't particularly bother me in regards to those problems, it'll get there.
You see the thing is, without those added features performance hits and rubber banding is bound to happen since there is alot more focus being put on the CPU, RAM and HDs. With this in mind Railworks is probably very much still a DirectX9 program which in some senses is a blessing a curse and the same time, while it can cater for a larger audience of older computers and still run to a decent standard it will lose out added levels of anti alias AF and other associated graphic boosts, also as noted in the above PhysisX isn't on the graphics card, it still remains to be calculated via the computer to they update the core engine to run PhysisX on the GPU and have railworks ultilise more cores.
Sound limitations are also present, Railworks only ultilises so many sound channels before it starts to cut out sounds, again this is probably a factor with having both PhysisX and sound processing all run through the computer, when the core change comes in there is a distinct possiblity that sound issues maybe resolved but don't quote me on that

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The thing is though, while there is a few negatives(or alot as some people seem to believe), Railworks does run fairly well within all the limitations imposed upon itself via using the older core I would also say there is certainly a great deal of entertainment to be had from Railworks once you got everything running, there is alot of DLC and alot of Freeware now available which 2years ago wasn't there and it does make Railworks worth it as a decent train simulator.
I think one thing which could be worked on, which probably would vastly improve Railworks in its current guise and in the future with its update is optimisation in regards to assets. Better loading of them and how they are stored and compressed could probably improve performance by quite a decent degree, for example, with all the assets I have + DLC I'm rocking a 35+ gigs of assets. While its nice to have all these routes and motive power that 35gig of asset folder alone does make me question on just how much is optimised and could be compressed or condensed. Its probably one of the big things which could change Railworks a great deal aswell. Strangely enough however, once you get into a large route (which loads for awhile), if you complete a scenario then wish to run a different one the route seems to load faster. Weather this is because its been in the memory just prior or Railworks has loaded the assets I'm not sure but optimisation in this area could probably solve alot.
While there are bad and good points of Railworks, it shouldn't deter from a actually pretty good simulator which, while it does have flaws in certain areas is probably one of the better on the market at this time and I would also note that RS.com does make the effort to keep us informed about new changes, new DLC and even post here on UKtrainsim, which alot of developers for other games wouldn't do. We have to also keep in mind, while RS team is bigger, its still a smaller company making its mark and in that process is learning what they can and cannot do, if you look back since Railworks was release there has been alot of changes and alot of new content which make it alot more appealing.
Maybe I've rambled abit and been abit inconsistant but that is how I see Railworks at this time, its getting there and there is changes to come, its just a matter of waiting, if we have to suffering abit of DLC releases so funds and the likes can be aqquired to develop better performance and what not then so be it, I'd also say that I'm willing to wait for it, as long as the developers keep community here, their site and facebook page and taking input without being snarky then its ok in my books, alot of other developers of games wouldn't keep that up.