If you want to turn off Selection Preview, perhaps because it makes it harder to snap accurately, go to the Selection tab of the Options command (found in the Tools menu).
Caption: Turn off Selection Preview by unchecking the boxes under Selection Preview.
Uncheck the selections in the Selection Preview panel on the left middle side of the tab. If you don’t turn Selection Preview off completely, click on the Visual Effects Settings buttons for additional selection preview features to change.
Caption: In the Visual Effects Setting dialog box, you can change how the selection preview is shown on screen.
Under Selection Preview Effect are options for how the selection preview appears on screen. You can select dashed lines, thickened lines, or both. Finally, click on Advanced Options to exclude certain types of objects from Selection Preview. The main benefit to excluding certain types is to speed up the preview.
Caption: In the advanced box, you can exclude certain object types from selection preview to speed things up.
Alternatively, you can change the settings of the following system variables directly at the command line.
SELECTIONPREVIEW controls the display of selection previewing. Its settings are:
0 = Off
1 = On when no command is active
2 = On when a command prompts to select an object
3 = Always on (default setting)
PREVIEWEFFECT controls the visual effect used to preview object selection. Options are:
0 = Dashed lines
1 = Thickened lines
2 = Dashed thickened lines (default setting)
PREVIEWFILTER excludes certain object types from selection previewing. Its settings are:
0 = Exclude nothing
1 = Exclude objects on locked layers
2 = Exclude objects in xrefs
4 = Exclude tables
8 = Exclude mtext objects
16 = Exclude hatch objects
32 = Exclude objects in groups
Add values to exclude more than one object type. For example, enter 12 to exclude both tables and mtext objects, but nothing else.