This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Say you have 75 mins of work and you work out that 25 mins and another 50 mins can be down in parallel (multithreaded) and the results combined so
you start the 50 min job in parallel (another thread) , do your 25 min work (main thread) and join to wait for the 50 min job to complete.
Total running time 50 mins , if you did all the work in one thread as you suggest 75 mins to do both sets (its faster).
"Eagles may soar but weasels don't get sucked into jet engines" SCJP 1.6, SCWCD 1.4, SCJD 1.5,SCBCD 5