Here are the similarities and differences in the C-Language Adapters:
C/CVI Standard Prototype Adapter Supported Features:
1) Test Functions can have a variety of prototypes - NO
2) Allows you to pass any argument to a test function directly - NO
3) Automatically passes a predefined set of common arguments to each function - YES
4) Code modules can be C source files, object files, or static libraries - YES
5) Can call DLLs created with MSVC++, Borland C++, Delphi, or another compiler - NO
6) Backward compatible with LabWindows/CVI Test Executive Toolkit - YES
7) Allows debugging C source files from TestStand - YES
😎 Allows debugging DLL functions from TestStand - YES
9) Can create source code from code templates - YES
10) Can use TestStand API within code modules - YES
DLL Flexible Prototype Adapter Supported Features:
1) Test Functions can have a variety of prototypes - YES
2) Allows you to pass any argument to a test function directly - YES
3) Automatically passes a predefined set of common arguments to each function - NO
4) Code modules can be C source files, object files, or static libraries - NO
5) Can call DLLs created with MSVC++, Borland C++, Delphi, or another compiler - YES
6) Backward compatible with LabWindows/CVI Test Executive Toolkit - NO
7) Allows debugging C source files from TestStand - NO
😎 Allows debugging DLL functions from TestStand - YES
9) Can create source code from code templates - YES
10) Can use TestStand API within code modules - YES
Since you stated that your main concern is differences in speed, the answer to this question depends upon how you are executing and debugging your code modules from within TestStand. If you are simply running a sequence in a "release" system (or non-debug), the adapters' performance are virtually the same. If you are debugging the dlls as they execute, and you are using "in-process" debugging with CVI on a C/CVI Std Prototype Adapter step, this is going to be slower due to the inherit overhead of this type of feature (in-process debugging is only available with the CVI Std Prototype Adapter). "External-process" debugging speed will largely depend upon the capabilities of the independent IDEs you decide upon using (external-process debugging is available with both adapters). Since, you said you would use CVI in either case, it will be the same with both adapters.
Hope this helps!
Jason F.
Applications Engineer
National Instruments
www.ni.com/ask