I did extensive testing this morning and I think I hit upon the issue. A strong possibility for the lag time is that exercises 1a and 1b uses definition queries for the LA river and city outline (from much larger files). Thus, I assume, the query may have to be done each time one zooms, pans, etc.?? I exported the LA river and city outline queries into shapefiles, added to the map document and then deleted the old layers (with definition queries). MUCH FASTER. Nothing over 7 seconds. I redid the test with the layers (again without definition queries) as geodatabase feature classes (but not inside the feature datasets�??thus, still GCS_WGS_1984). Same result�??FAST. Thus, no difference between shapefile vs. feature class. Thus, to me, this clearly suggests that the definition query is slowing things down considerable, and, secondary�??the reprojection on the fly.
Thus, my suggestion of users of your book would be that they export their definition queries into new shapefiles/feature classes, thus avoiding this potential issue. However, you should note that even after doing this occasionally the basemap layer would not display (although it is in the table of contents). Re-adding the basemap layer or restarting ArcMap and then re-opening map document fixes this issue (this only happened once to me after exporting the layers�??and ridding my map document of the definition queries). ArcGIS version: ArcInfo Desktop 10.0 service pack 4.
