It may not be about optimization, but about user experience. You may have to be clever and think outside the box. Can you save a snapshot of all that work so that the next instance doesn't have to do it before showing the window? And then assuming it has to do the work (which may not be necessary if it just started up--once a day is probably sufficient), it can redo the work in a separate thread.
Eclipse already does non-critical background tasks on separate threads, and non-critical startup tasks are done in "deferred early start" queue, which is emptied after initial startup.
Normally Eclipse IDE is not something like Vim, which you enter and exit 10 times a day. It just lives there and you work with it. 10 seconds in the morning for a tool that big is very acceptable, esp. after considering that everything is instantaneous after that 10 seconds.
