If you insert tuples with COPY into a table created or truncated in the same transaction, at the end of the COPY it calls heap_sync.
But there cases were people use COPY in a loop with a small amount of data in each statement. Now it is calling heap_sync many times, and if NBuffers is large doing that gets very slow.
Could the heap_sync be safely delayed until the end of the transaction, rather than the end of the COPY?