No, it isn't. Seriously, I've not seen any real evidence of this.
Move a window. See how the window lags behind the cursor? (Or the cursor lags behind the window, i don't remember). That's one. Now scroll in either chrome or firefox. Less than 60fps. Enable compositing - now you've lost vsync with any kind of accelerated video (unless you enable that ugly hack in intel drivers, which slashes performance in half). That's just the top of my head.
If anything it's one of the best performing systems out there
Even the current developers of Xorg disagree with you
On some cards with the "glamour" driver, all 2D operations are done on the graphics card using shaders. Never mind the EXA and XAA systems which have also used older 2D acceleration.
That's exactly ONE driver - intel. And glamour is a HACK. It does a double-reacharound to do what wayland does by default (and any other sane windowing system). With adding the X protocol cruft with all it's stupid extensions on top.
Yes it does and you're just making shit up.
No, I'm not. First it was XAA, which did shitall. Then it was RENDER, which supposedly did what glamour does now. Oh, and let's not forget about EXA, FMA and other 3 letter acronyms which were supposed to "fix it". I read Keiths blog regularly, I remember his benchmark for intel, when he worked on SMA and GLAMOR (too lazy to link to his benchmark, but you can use google). And let's get this straight, all those "acceleration" extensions were for one purpose - going AROUND the X protocol, because it was designed for LINES, not bitmaps.
So using shaders to do 2D stuff is a "hack" in your book? How does that make any sense whatsoever?
No, doing 2D in shaders is exactly what you want. Gluing that to the X protocol is patently stupid and counterproductive. It's a stopgap until the Linux desktop adopts wayland.
Did OSX get some hardware accelerated features first? Yes, but it didn't get hardware assisted rendering of any sort first
Actually, it did.
OS X 10.4 (Quartz Extreme 2D) - 2005
Win 7 (DirectDraw) - 2009
Linux - about now-ish, and STILL not fully adopted. Unless you can point me to a data source that claims otherwise. And no, hacks like glamour (which got release a fucking month ago!) or Xgl don't count (it doesn't matter really, since it was just compositing)