Loading time (please wait screen) goes from ~3s to ~1s (on a second run tests to make sure files were cached for both tests - which actually isn't even a fair test as I would have wanted them both not to be cached) on a p3-600 640MB RAM once the entire DAT contents are extracted AND the DAT files are deleted/moved elsewhere.
There are two reasons it is faster. The first is like FOT, the game looks for files on the HD - regardless of it being in the DAT file, if it finds it loads it, failing that loads the one in the DAT. So time is wasted checking for the file (regardless of the DAT file being there or not). Since it checks for it, might as well have it suceed and not try to load it from a more convoluted system of the DATs. The second is simpler to explain: the DAT format features compression, which obviously consumes some time whilst decompressing it.
Other more generic tips (and sometimes obvious)
- Use humongous installation (duh)
- Make sure the 1.02 patch is applied (it should be if you're using that 1.05 mod)
- Make sure no other (normal) apps are running (and other users are logged off on XP)
- Make sure to defrag - even if using NTFS (specially after the extration tip).
- Make sure to have a well setup computer (ie not tons of processes in the backround doing useless stuff; if you know how to optimize your OS for RAM and varous other things, do so)
- Possibly disable virus scanning software during play time.
- Copy the music files instead of inserting the CD-ROM. You'll need to update Fallout2.cfg... You can even omit them altogether
I recently installed XP on a Celeron300 (non-A!) w/64 MB RAM. I should install FO2 on it and see how it runs
The main reason the save times get longer is because of the inventory you store. Not just on you, in your trunk and NPCs too!