Are you sure you're looking at the right conf file? There are a bunch of test ones left lying around. For bridge, it's /etc/snort/snort_bridge.conf or via the GUI (Router is snort7.conf & snort8.conf). It should have been:
Old:
config detection: search-method ac-nq search-optimize max-pattern-len 20
Everyone should add the no_stream_inserts as this is a speed optimization. Only if you plan on adding the trojan rules or more than 6000 rules do you need the memory optimization which adds the split-any-any.
New: (everyone not using the trojan or under 6000 rules)
config detection: search-method ac-nq search-optimize max-pattern-len 20 no_stream_inserts
New: (everyone including the trojan rules or over 6000 rules)
config detection: search-method ac-nq split-any-any search-optimize max-pattern-len 20 no_stream_inserts
Running the latest OpenWrt stable release