One of the major improvements in the new Jumpshot and SLOG-2 is the scalability in terms of visualization performance. As shown in Figure 3.6, there are 7 bands of preview states covering the whole canvas in the initial Timeline window. By incrementing the parameter, INIT_SLOG2_LEVEL_READ, by 1 in Preference window as in Table 3.10, the initial Timeline window can be redisplayed and is shown in Figure 4.3. The new Timeline window has 14 bands of preview states instead of 7. The increase preview resolution does offer a more detailed description of logfile but at the expense of graphical performance. Because every increment of INIT_SLOG2_LEVEL_READ will roughly double the number of drawables to be iterated during every zooming or scrolling4.2. The biggest demand of graphical performance occurs when the zooming to the level of only pure real drawables from the lower zoom level. The value of INIT_SLOG2_LEVEL_READ should be chosen so that Jumpshot does not appear to be too slow during the zooming to the pure real drawable level. For a fast graphics system, INIT_SLOG2_LEVEL_READ should be set higher than the default value 3, like 4 or 5, so that more information is present during each view.
Another parameter also signifcantly affects the graphical performance
is ARROW_ANTIALIASING in Preference window. Setting the paramters
to ON will force Jumpshot to draw all arrows including preview arrows
with anti-aliasing lines. This proves to be an expensive graphical
operation4.3. Except when high quality picture is needed like during screen capture
for picture or when antialiasing lines are drawn with graphics hardware
support, it is not recommended to turn on ARROW_ANTIALIASING.