FOSS gamedev and creative worlds

well the title is self explicative (or how to write it XD)
i'm new in minetest , so i tryed it first in 0.3 singleplayer then , find it very funny and compiled 0.4
the problem is that i can connect only to one server , the others take ages to load , and the only who load quickly appear very slowly (and after sometime the game start to lag really a lot , like i'm playing skyrim at max grapichs)

my pc is a :
p6024it whit :
2.2 Ghz triple core processor
Nvidia G100 videocard
OS : Kubuntu 12.04 LTS X64 (Italian)
4GB ram

if anything else is needed only ask
thank for help !
(and sorry for bad english LOL)

"self explicative" should be "self-explanatory". :P
The others take ages to load because they're down.
Also, "nvidia G100" isn't a grapics card. I don't know what you mean by G100...

http://www.nvidia.it/object/product_geforce_g_100_it.html
(nvidia Geforce G100 [a shit of video card .-.])
all servers down ? O_O
(sorry english is not my mother language XD)