I don't necessarily agree with the tone, but I agree with all the sentiments. The issues you're having can be exacerbated by a slow or old computer but the issues you're bringing up are inherent to SU no matter what PC you have to a great or lesser degree.
File save times can be slow and to make matters worse file sizes are often larger than they "should" be which compounds the issue. By comparison, 3ds Max can save large amounts of geometry pretty quickly with small file sizes (there's even a "compress on save" option that can reduce file sizes by 75%). There are, of course, ways to quickly bloat your file, but even if you utilize good SU file management, the issue is still far from ideal.
I won't go into detail reiterating all of your other points but suffice it to say I fully agree that at this stage better UV mapping, unbroken material management (The inability to save/delete a material in a moderately sized scene, I think, constitutes as broken), etc.
-Brodie