Most likely, but in the vast majority of cases, that additional speed does not matter. In the time that I’ve been working in Integration Server, I’ve never had to redo something from FLOW to Java due to speed.
The 3 rules of optimization are:
- Don’t.
- Don’t yet.
- Profile before optimizing.

If you don’t measure, you don’t know if the approach is actually faster. And depending upon the specifics of the integration, an additional 5 seconds of processing (or even minutes) may not matter in any way. For example, unattended data sync interactions where there is not a user waiting for a screen, it matters not at all if the data arrives 15 minutes later.
Runtime speed is not the only factor to consider when developing a solution. IME, runtime speed is almost never a constraining factor.
#Integration-Server-and-ESB#Flow-and-Java-services#webMethods