Make all visible Block Surfaces invisible,those the player does not see. This
increased your Frame Rate and many Protals in ure Level would be "Deleted".
Example:
Right Click on ure Block--->Properties--->Surface--->Flags--->Then all Surfaces those the Player doesnt see, set "None"...
Hope u understand this and ure Level works fine ^^
cYa Sebastian
Tutorials:
[Blender]Terrain creation ENG/GER
[Blender]Low Poly Tree Modeling
[GIMP]Create a Texture for Terrains
CLICK HERE