Build time of XPages application containing several JARs, Java sources and ~50 XP/CC elements takes about minute to build on server via WAN. I have replicated application to local, build time dropped to ~10s.
Since few days ago build of local application is extremely slow, about 2-5 minutes. After some experiments there is workaround: to disable TCP port in location document - it drops build times to just few seconds. Even tho it works, it does not help much - testing requires user to be authenticated, so I need to replicate design changes to remote or local server - and that means to change location (online/offline) every time.
UPDATE 2013-04-04: I have duplicated my current location document and removed home and directory servers. To my surprise, with this location build times went back to few seconds - with TCP port enabled so replication is possible. Bigger surprise was the fact, that returning home/directory servers back to new location did not reproduce the problem - in fact they do not affect performance. I know it because I have renamed current location document and everything went to normal. From my understanding, "something" in client configuration was connected to location name. Thanks to Simon's tips I will investigate further.
The question is still open: I am looking for some (eclipse) preference controlling this behavior - unintended communication with server during build of local application.