I remember having something similar on my old pc. here is what I used:
Main settings:
Max segments drawn-2500
field of view (FOV)-85
shadows-OFF
normal/emissive maps-OFF
lighting quality/ray trace steps- 128
Procedural background-ON [1024 resolution]
texture pack- 128 [it shouldnt impact you that much]
Advanced Settings tab:
AntiAliasing samples: 0
Bloom-OFF
VBO bulk mode-128
Vertical sync-OFF
everything else is fine as default(shoudl be)
Config settings: [singleplayer only,depends on other server owners]
CONCURRENT_SIMULATION = 128
SECTOR_INACTIVE_TIMEOUT = 12
SECTOR_INACTIVE_CLEANUP_TIMEOUT = 10
UNIVERSE_DAY_IN_MS = -1 [this one is important]
PLANET_SIZE_MEAN = 115.0
PLANET_SIZE_DEVIATION = 35.0
SECTOR_AUTOSAVE_SEC = 400
dedicated ram?
Depends if you have 64bit OS and 64bit JAVA
if you have 32bit
early gen: 256 MB
initial: 512 MB
Max: 1024 MB
if you have 64bit:
early gen: 1024 MB
initial: 2048 MB
Max: 4096 MB