Welcome to the board!
When i come to dock at a space station the whole system slows down to unplayable. I have reduced the screen size and set all the adjustable setting on the ingame menu to the minimum, but the same thing still happens. My comp is a 3ghz Dell with a Radeon x300 card and i have 1 gig of memory.
That's a bit strange. I know that Oolite is slowest when viewing the galactic chart (I really don't know why), but when you dock it should not be a graphics issue and the main screen there is not causing slowdowns for me.
Did you install many OXPs to the AddOn folder? Vanilla Oolite won't use much memory, but if you install many additional things, it can go up to over 1 gigabyte (e.g. with TONS of ships and viewing every single of them in the beginning) thus my initial guess would be that your system is beginning to swap, although I fail to understand why it should happen when you dock.
Maybe it would help if you post your logfile from such a flight here, it will at least list the OXPs used (if any).