Conversion performance varies widely depending on the input document size and complexity, input and output formats etc. Since conversions are done by OpenOffice.org, raw conversion time is not something that can be improved by JODConverter.
Just to give an idea the following table shows some benchmarks for converting different ODT documents to PDF:
(Tests made with OpenOffice.org 2.3 on a laptop with a single-core Mobile Athlon 64 2.6GHz processor and Ubuntu Linux 7.10.)
In general, conversions to/from OpenDocument take less time than equivalent conversions involving other formats since OpenDocument is the native OpenOffice.org format. (E.g. ODT to PDF is faster than DOC to PDF.) Other factors affecting performance include the presence of graphics, charts, and other objects in the document, macros etc.
The bottom line is that you should make some benchmarks of your own - with documents of the types and complexities required by your application - to understand if the performance is adequate for your purposes, or if you need to throw more hardware at the problem.