>Hi Al,
>
>>
>>As for RAM, take a look in Task Manager at RAM usage (Commit Charge) while running a maximum app load. If it's 2GB or less, you're not likely to see a lot of performance improvement going to 64-bit.
>>You may say, well, the disk cache has doubled, that's going to improve performance a lot. That's not really the case - a cache is a good example of Pareto's Law, you get most of the benefit with not too many resources applied. For example, a 1GB cache may give 80% of the performance improvement you'd get with a 2GB cache.
>
>One exception quite possible for users of this forum: It might be different if the app is is database app with where the table space is large.
>We must stay with some of our longrunning tasks in 32 BIT, and realize different RAM size availability, as some of the machines can only adress 3GB, while others have 4 GB giving them 3.6GB usable RAM.
>
>We are running vfp with 256MB, as sometimes run into errors with more memory given to vfp. I ran for kicks the app with a middle amount of data (about 12 GB) under 2GB of RAM on a normally 3Gig machine: runtime went up from 5H to 8H by decrassong disc cache size from 2.6GB to 1.6GB.
>
>Yes, it falls under Pareto law - very astute observation - but the cost added from accessing not the cache is between 10 and 100 times the original cost. This is verified, as I have extensive time measurements with high performance counters throughout the application. Only a few operations on large tables take very much longer, resulting in substantial speed decrease.

If you've got a highly tuned app taking 5+ hours to run, that's a lot of crunching. You're right, if you're working with largish data sets you can benefit from more RAM for disk cache - like I mentioned earlier with video editing. You might be a good candidate to run a 64-bit Windows OS with, say, 16GB RAM. Although VFP would run using only 0.25GB on WOW64, hopefully the host OS would snoop the disk I/O and cache the full 12GB eventually. Get rid of those expensive cache misses entirely.

You're probably one of the few business users who can actually make use of a fast CPU and fast RAM.

Out of interest, what are the types of errors you see with VFP when you give it more than 256MB?