Hmm... this could be a memory fragmentation issue.

It could be, that after all your spot renders, although you have 1.2 gig of RAM left, it's not contiguous, but scattered around in tiny-weeny little pieces, with other, used, chunks in between.
So when Vue then requests a new (largish, contiguous) chunk, it can't be found. A symptom very similar to disk fragmentation, except that while fragmented files can be handled by the OS, most software can't deal with fragmented memory.

Or, of course, it might be something totally different....

Cheers,
Diolma