I've had Minecraft since it's Alpha days and I completely agree with you burnov. I remember when I could stand on a mountain with Far render distance and see for what seemed like miles. Now all I see are loading chunks.
I'm pretty sure they also reduced the maximum "far" draw distance which is rather disappointing.
I sure hope it's fixed. I remember back in Alpha when I would get no lag at all, and every chunk around me would be loaded in a second. Now, I'm forced to deal with huge amounts of lag, and this chunk loading speed. It's really upsetting :/
I've not noticed. Been playing since 1.2.5. I was going to say it was probably because I don't have any super long railways, but I do. Thing is, they are underground. I've never really liked the "scenery". Everything looks pretty much the same, unless you do some landscaping or building. Any time I've wanted to survey an area from a high spot I've never had issues with draw distance (I keep it on full).
I think the "problem" was fixed, it was originally intended as a performance optimization (that is, more time was being spent "pumping out the FPS" that would be more effectively used bringing in the chunks. Keeping the setting in "max FPS" will give you the same effect, but balanced should change that. It won't be as good as it used to be, since it used to be that chunk loading/generation would take priority over everything else, thus FPS drops into the 5-10 range on lower-end machines while riding boats into new territory. The issue wasn't as pronounced when moving over already generated terrain, since it didn't take as long to load a chunk in as it does to generate a new one.
I do extensive exploration of new areas using Boats, and not encountered this issue, Although I can come close if I set it to "max FPS".