Hi,
| 1. What is the max size the namemapping file can be? |
There are no special limitations.
| 2. What is the optimal size I should aim for before taking a performance hit? |
The optimal size of name mapping files depends on the test where the mapped objects are used. Of course, if the files are big, TestComplete may consume a lot of memory. However, we will improve the situation significantly in the next major version of TestComplete.
| 3. Are there any "best practices" for namemapping management? |
I recommend that you watch the 'Creating Reliable Tests For Dynamic Objects with Name Mapping' screencast that will help you understand the Name Mapping functionality better:
http://smartbear.com/support/screencasts/testcomplete/reliable-tests-for-dynamic-objects/