yeah, clip plane is always the first thing.
however... lik you said you can no longer see far.
when i turned of the shader settings, i could still see far, and didn't notice much change at all.
that is the only ajustment i used to make, the clip plain, if i got a little laggy on raids, i would turn it down. well, when oow came out, i discovered lag, RSS i hated that zone, only zone in the game i got lag, mouse lag, mouse would get slugish. so i avoided RSS. now here comes DoD, undershore i was, but the zone off it to get to stoneroot made my cpu act just like RSS. thats when i started playing with more settings. the shaders fixed it.
i run 3.2 gihtz cpu with 2gig ram. can run 4 accounts of eq at once, yet RSS lagged me.. was weirdest thing.
might just look into another vid card, i have a radeon 9200 series, so that might be the problem, i don't know, was the card that came with the cpu.