I have just been playing around with a freeware defrag programme called JKDEFRAG. Whatever it was doing, it took a long time to do - have been using the default WindowsXP defrag before this. When I started FSx today for the first time , it took 90 seconds to get from selecting the defaut startup flight to being on the ground ready to go. BUT - I shut FSx down and restarted it - and this time it only took 45 seconds.Any comments please?Barry

I've noticed that the second time you launch FSX it's quicker. I only use the Vista default defrag and I've always assumed that it's quicker because the program bits remain in memory when you exit, and so they don't have to be read from the HD.Mike.

I'm not 100% sure about this but, if MS wrote FSX to leave bits of itself in memory when shut down then they've done a poor job of developing the application. I seem to remember that when an application is shut down, all memory locations associated with the application should be cleared out otherwise there is a possibility of a security breach or compromised memory locations. At least that is my recollection from my ancient past when I developed software.Often, when you first run FSX, the application has to build the database of scenery objects - especially if you've added something since that last time you ran the program. I think this also applies to addon aircraft. The second time you run FSX, the application doesn't have to build that database if you haven't added anything since the last execution. This may be the reason for a quicker load.Just a thoughtfb

I've noticed this on occasion. The clearing of memory is only for the program executable itself. There may be some DLLs cached or the hard disk cache(s) may contain needed data.

As I understand it, all programs leave something in ram after they are closed. You can get utilities that will clear ram for you. I have noticed that both FS9 and FSX start much quicker the second time. Vista has a system called superfetch that will load aspects of the programs you use the most based on amount of usage and time of day that you use them. I have that feature turned off.Bob

Start up any application, close it, and immediately open it again and you'll see it open faster the second time. Try it with Firefox!Jimhttp://www.hifisim.com/banners/hifi-community-sigbanner.jpghttp://www.hifisim.com/

I think in the case of FSX it may be that files are left in the system cache. Any RAM not required by OS or apps is allocated to cache, under the theory that no RAM should be left unused. scott s..

In addition to what has been said, WindowsXP has what is called a "Prefetch" where it catalogues frequently-used data and stores this in the /Prefetch dir.FS fits this scheme perfectly because it is a high-mem app but it loads the same data (mostly) each time you start the program.This is not the same as memory caching. Nor is it the same as Vista's "Superfetch", which is conceptually similar but not the same as what XP's prefetching does.But in addition, as the others said, system mem caching also has a lot to do with the speed increase, in fact it has the most impact.The comment about the OS needing to clear all of the data from mem is a valid point, but let's not forget--the winXP memory manager is pretty good compared to what it used to be in the 90's--if that system memory is needed by a new application, the memory manager will generally immediately free all of that used memory, kicking out any FS data that might still be in there. It's not foolproof, certainly though.RhettFS box: E8500 (@ 3.80 ghz), AC Freezer 7 Pro, ASUS P5E3 Premium, BFG 8800GTX 756 (nVidia 169 WHQL), 4gb DDR3 1600 Patriot Cas7 7-7-7-20 (2T), PC Power 750, WD 150gb 10000rpm Raptor, Seagate 500gb, Silverstone TJ09 case, Vista Ultimate 64ASX Client: AMD 3700+ (@ 2.6 ghz), 7800GT