MP Replay - Out Of Stash Space

[◄Chuck►]

Other way around. That message is just the symptom, but the actual cause is that you're lagging out of the server.

There is no official explanation on this matter but from what I've heard over the years, when lfs saves the replay to disk, it saves the remote data and the local data in a chronological stream. If the remote stream fails to work (lag or other networking issues), it can't combine both streams any more.
Since there is always some delay over network, there exists some little buffer, that's what I think, is the so called "stash space". So the local data waits in that stash space until the matching data over network has arrived (with matching timestamp or whatever).
However, you can see, if the network gets worse, more and more local data gets into the buffer, waiting for it's remote counterpart. But at some point, the buffer is full, and the whole system collapses.