Start by setting the correct baud rate. Position information is always stored in memory. The size of this buffer will determine the number of frames that can be recorded. When recording to disk, the capacity of the disk and the space available in memory for the position information will determine the length of recording possible. Opting for fewer polygons gives faster rendering but lower resolution.
More polygons give better resolution but slower rendering.
You should set this control according to the capabilities of your computer's graphics system.