- For Java users, there is a performance penalty due to the well known fact that JVM(Java Virtual Memory) is a memory hogger. Scalability is an issue as well. - If you have a requirement of adding custom algorithms for indexing data, you might face a little difficulty, as there is not much information available either in Lucene forums or mailing lists. Though community support is excellent for Java users, for other area specific Programming Platforms like Perl, and Delphi, it is a bit difficult to get solutions for your problems, as the tool is still not that stable in these platforms and is still in the incubation phase.