>>>Hmm, in the limited work I've done with comms ISTR it's common practice to use buffering, where you let X bytes or kilobytes accumulate, then process. Requiring the listener to handle incoming bytes individually in real-time can expose you to (as you point out) GC, or OS or even (in your case) VM context switching.
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>Because VFP doesn't handle chr(0) very well it needs to be byte by byte.

If you keep getting intermittent failures you might have to work around that.

>>>There is also a 16MB size limit for a memvar (and presumably object property). Do you get any messages approaching that size?
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>Yep- but it's also documented that variables can get up to >600Mb if you're just adding to the same variable, but you can't assign it to a new variable. Still another good reason to refactor.

I just did a quick test in the Command Window:

lcBig = SPACE( 16000000 )
lcBig = lcBig + SPACE( 16000000 )

By my count I grew it to 31 * 16000000. Trying to add another 16000000 spaces made VFP crash with a C5 (VFP9 SP2 7423).