The LC III was a significantly faster computer than the
LC II. Running at 25MHz on a 32-bit data bus,
the LC offered nearly the same performance as the IIci. The primary
difference was that the LC III used an extended version of the LC PDS
slot - most cards were designed for 16-bit access, so adding a video
card or ethernet port made the computer run a bit less efficiently
than the more expandable IIci.
Significantly faster than the LC II, the LC III also broke the
10MB RAM barrier, allowing expansion to 36MB. This was the first Mac
to use 72-pin SIMMs.
The LC III will support 16-bit video if you select the 640 x 400
pixel mode under Options in the Monitors control panel, then restart