This depends a bit on how much time you’re willing to invest, and what amount of efficiency you would like to reach.
Tinder is a small library, but this does not necesarily translate into a super low memory footprint. There is a bit of caching going on in the JID class, for example, that is more tailored towards server-sided setups. You should be able to weed this out pretty fast if you run through the code, but doing this would require you to modify Tinder itself. On top of the caching, Tinder enforces the full set of requirements and restrictions defined by the XMPP spec on JIDs (although you can switch this off). This is a pretty CPU-intensive task.
Smack on the other hand offers a lot of client-specific code that Tinder does not have. You’d have to write this yourself if you choose to use Tinder.