Hi,
There is an article here https://wiki.apache.org/tomcat/HowTo/FasterStartUp that discusses the taglib scanning that may be relevant depending on which version of Tomcat you are using:
"A note on TLD scanning: In Tomcat 7 and earlier the TLD scanning happens twice,
first, at startup time, to discover listeners declared in tld files (done by TldConfig class), second, by JSP engine when generating java code for a JSP page (done by TldLocationsCache)."
In later versions (>7), the second scan is not performed which is why, after the modules are extracted into the webapp’s WEB-INF/view/module directory, a second scan is required.
I stand to be corrected but that I believe is the reason why.
Cheers,
Ben