Both fgdb and esri's shape access suffer from size/performance correlation. It is strange, because when I use ogr to add fields, insertion is constant. Good example of 'Schlemiel the Painter's algorithm'[0]. Never thought I would see an example of that now a days. Attached is a graph of insertion times over the course of 1000 AddField calls. I also tested the copy of the mem to gdb, and that seems to be the best way to go in arc:Output of test over 1000 Add Field calls:C:\Users\kshannon\Desktop>c:\Python26\ArcGIS10.0\python.exe add_field_test.py
Creating feature classes...
Feature classes created.
GDB(Total:940.140323837,Max(924):1.72044671624,Min(60):0.582889467023,Average:0.940140323837
SHP(Total:352.133845124,Max(994):1.01701894889,Min(2):0.0293058087336,Average:0.352133845124
MEM(Total:52.2060125065,Max(994):1.01701894889,Min(2):0.0293058087336,Average:0.0522060125065
MEM to GDB:2.62204624813
OGR(Total:37.934927268,Max(994):1.01701894889,Min(1):0.0222360889709,Average:0.037934927268
Deleting feature classes...
Feature classes deleted.
The values in parentheses are the iteration at which the min/max occurred. Thanks for the help.[0] http://en.wikipedia.org/wiki/Schlemiel_the_Painter's_algorithm