Hello, the store and store-server examples on github (https://github.com/rhomobile/store and https://github.com/rhomobile/store-server, respectively) have a "customer" model and adapter demonstrating search. The search method is always executed synchronously in the server (until the next version of rhoconnect when we introduce async functionality) and will return data as quickly as your adapter code and backend can process it.
The only real way to tell with this particular dataset would be to try it with some ruby code, a simple test of calling it in ruby in irb would be sufficient to get an idea. We do have customers that use search extensively for very large (100MB+) datasets and it works well. Note in some cases the backend service endpoints need to be adjusted to fit your mobile use case.