What Jerry says is correct.
There is no culling control in the editor for the editor.
There is a clip mode which hides objects above a certain height to aid in placing things inside of stuff.
Press Tab once while in the editor. Hold the Ctrl Key and scroll the middle mouse wheel to control the clip height. the height status is in the right in the status panel below.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit, Screen resolution 1680 x 1050.