Yes its normal if you have full lights on. If you want a faster preview load turn it to best for performance, but leave it for build game as best for quality and don't worry about it doing it every time. Cause once you have build the level once it loads the dbo and dbu to run it the second time and so on. So it wont take long the next time you run the game unless you added something to the map then it will have to calculate it all over again. But if you thought that 5 min was bad you should of seen fps creator x9 when it first came out it took like 12 hours or more to calculate the lights on full even in a small level..
