Here's my practical experience from work. Our scripts usually will glob in large amounts of data, and sort through them via hashtables and such. Such code frequently consumes 100% of the CPU for long periods of time, which indicates that we may be reading in too much data.

I have found, on our 500- and 700-mhz machines, that 50 megabytes of data is too much for hashtables. The operating system may start churning all that data to a disk cache, in which case you may be in for loooong processing times. Or, for truly vast amounts of data, perhaps the program will simply die due to an Out Of Memory Error.

On the other hand it appears that 1 megabyte of data is not too bad for us. It seems to go into hashtables ok. Of course, we have 256 meg of RAM, so 1 meg here and there is "no big deal".

Your mileage may differ.

rje