This is not very clear.
Can you describe what it is you're automating? Assuming the application is Excel, you can either use a Macro, or a VB module.
The speed that it executes at isn't normally an issue, unless you're doing something repetitive.
As a programmer I'm sure you'll already be aware that there are a million ways to write a piece of code, nota ll of which will be fast.
With excel, first thing to do is make sure you're not doing anything unneccessary - make sure you switch off the display when you start the operation, and switch back on when you;ve finished. Screen rewrites can really slow things down. (Make sure it works first though, you won't be able to break back in if you get an error)
More data please . . .