Rubat explains "Render queue too large, flushing!"

In #lua-help, A1steaksa asked what causes Render queue too large, flushing! when rendering an IMesh. Rubat explained the multicore rendering queue is too large: over 32 MB of vertices or indices, or over 15 MB of data in the queue. He named mat_report_queue_status for stats. full metal sergeant 228 said he hit it with too many particle systems.