Improving the performance of LVDS DDR at 200MHz

I'm surprised the data-bus routing is so high.

That being said, and not looking at what you have, I have done emulated differential drivers(HSTL) and usually see about 600ps of skew compared to the clock. The majority of this is on-die variation. It hurts because it cuts both ways, i.e. it models the clock as slower than the data for setup, and longer for hold.

There is nothing that will reduce ODV, except going to a faster speed grade. Also, one thing to note is that ODV does not take into account locality. Two outputs right next to it have the same ODV as two I/O on opposite sides of the die, so there might be some pessimism with well laid out I/O, but there's no way to be sure.

If you go to True LVDS, the channel-to-channel skew drops to 100ps, which is fantastic. This does not use a global clock and everything is dedicated. It's really around 800Mbps-1Gbps where you should go to that, depending on the situation.