Pete Muir opened an issue a few weeks ago (https://issues.jboss.org/browse/JBIDE-12224) because he found that the JAX-RS tooling was sometimes taking too much time to build. He also attached a video to show what's happening on his machine: http://screencast.com/t/pHBqxVas4

Now, at the tooling level, here's what's happening: a set of jars are added to the classpath, and as part of the project build, the JAX-RS builder searches for some JAX-RS annotated types or methods in those new jars, using the Search API. Hélas, Eclipse needs to index those jars, which sometimes takes a few seconds.

Now, as opposed to the CDI specification where the jars should have a marker file (META-INF/beans.xml), JAX-RS does not mandate anything similar, which means that the search includes all the jars..

Here's an example of the code that deals with annotated types search (in ws/plugins/org.jboss.tools.ws.jaxrs.core/src/org/jboss/tools/ws/jaxrs/core/jdt/JaxrsAnnotationsScanner.java) :

private static List<IType> searchForAnnotatedTypes(final Class<?> annotation, final IJavaSearchScope searchScope,

final IProgressMonitor progressMonitor) throws CoreException {

JavaMemberSearchResultCollector collector = new JavaMemberSearchResultCollector(IJavaElement.TYPE, searchScope);

SearchPattern pattern = SearchPattern.createPattern(annotation.getName(), IJavaSearchConstants.ANNOTATION_TYPE,

IJavaSearchConstants.ANNOTATION_TYPE_REFERENCE | IJavaSearchConstants.TYPE, SearchPattern.R_EXACT_MATCH

| SearchPattern.R_CASE_SENSITIVE);

// perform search, results are added/filtered by the custom

// searchRequestor defined above

new SearchEngine().search(pattern, new SearchParticipant[] { SearchEngine.getDefaultSearchParticipant() },

searchScope, collector, progressMonitor);

return collector.getResult(IType.class);

}