Gets or sets how many bytes of a non-seekable stream are copied into memory when a document is opened from it; a longer stream is copied into a temporary file, deleted when the document is disposed, and read from there. Default 64 MiB.
public long StreamBufferLimit { get; set; }
ISO 32000-2 §7.5.1: a file is read at random through its cross-reference table, starting from its end, which a non-seekable stream cannot do, so it is copied once at the open boundary. A seekable stream, a path and bytes are never copied: they are read in place or memory-mapped as objects are used.