Since Wireshark will finally display (into "packet list") all packet at the end (no ?),
I do not think there is a difference.
Did you have removed "colorize packet list" option (into view menu or using icon into toolbar) ?
When "colorize packet list" option is set, the dissector analyse the entire data of the packet.
When "colorize packet list" option is unset, the dissector analyse only the "header" of the packet.
This could give a big performance difference.