"enable smart optimization" is an option that can be set for each module. Is on by default. from the v4 docs from the v2.7 docs of a similiar worded setting. Actual observed behaviour is with the setting off and advanced heuristics turned on, when loading my pdf viewer I get a 5+ second pause on loading on every time the app is loaded. When the setting is turned on I get the 5+ second pause the first time I load the app but then the app loads as fast as it does when the advanced heuristics is off. It then is slow once after either adjusting options or a defenition update. This behaviour is the same as what the 2.7 document is saying, a cached lookup result after the first lookup.