The scanning can be improved.
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/javax/servlet/javax.servlet-api/3.1.0/javax.servlet-api-3.1.0.jar in 74ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/apache/taglibs/taglibs-standard-impl/1.2.1/taglibs-standard-impl-1.2.1.jar in 92ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/Code/git/jetty-slow-startup/target/classes/ in 29ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/com/fasterxml/jackson/core/jackson-annotations/2.4.5/jackson-annotations-2.4.5.jar in 66ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/javax/servlet/jstl/1.2/jstl-1.2.jar in 188ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/javax/servlet/javax.servlet-api/3.1.0/javax.servlet-api-3.1.0.jar in 13ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.4.5/jackson-databind-2.4.5.jar in 384ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.4.5/jackson-core-2.4.5.jar in 92ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/security/spring-security-taglibs/3.2.7.RELEASE/spring-security-taglibs-3.2.7.RELEASE.jar in 20ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/security/spring-security-acl/3.2.7.RELEASE/spring-security-acl-3.2.7.RELEASE.jar in 68ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-jdbc/4.1.6.RELEASE/spring-jdbc-4.1.6.RELEASE.jar in 205ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-tx/4.1.6.RELEASE/spring-tx-4.1.6.RELEASE.jar in 147ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/security/spring-security-core/3.2.7.RELEASE/spring-security-core-3.2.7.RELEASE.jar in 223ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-aop/4.1.6.RELEASE/spring-aop-4.1.6.RELEASE.jar in 131ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-beans/4.1.6.RELEASE/spring-beans-4.1.6.RELEASE.jar in 272ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-_expression_/4.1.6.RELEASE/spring-_expression_-4.1.6.RELEASE.jar in 99ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/security/spring-security-web/3.2.7.RELEASE/spring-security-web-3.2.7.RELEASE.jar in 149ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/aopalliance/aopalliance/1.0/aopalliance-1.0.jar in 4ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/security/spring-security-config/3.2.7.RELEASE/spring-security-config-3.2.7.RELEASE.jar in 140ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-webmvc/4.1.6.RELEASE/spring-webmvc-4.1.6.RELEASE.jar in 211ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-web/4.1.6.RELEASE/spring-web-4.1.6.RELEASE.jar in 180ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-context/4.1.6.RELEASE/spring-context-4.1.6.RELEASE.jar in 243ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/springframework/spring-core/4.1.6.RELEASE/spring-core-4.1.6.RELEASE.jar in 188ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned file:/Users/joakim/.m2/repository/org/webjars/extjs/5.1.0/extjs-5.1.0.jar in 1981ms
2015-04-16 15:05:11.418:DBUG:oeja.AnnotationConfiguration:main: Scanned 2 container path jars, 21 WEB-INF/lib jars, 1 WEB-INF/classes dirs in 2321ms for context o.e.j.m.p.JettyWebAppContext@57fbc06f{/backend,[file:/Users/joakim/Code/git/jetty-slow-startup/src/main/webapp/, jar:file:/Users/joakim/.m2/repository/org/webjars/extjs/5.1.0/extjs-5.1.0.jar!/META-INF/resources],STARTING}{file:/Users/joakim/Code/git/jetty-slow-startup/src/main/webapp/}
This is on OSX, using Java 8u31.
The extjs-5.1.0.jar only took a scant 2 seconds to scan.
The scan ignored most (if not all) of that jar's contents anyway (no *.class files).
The startup, on the other hand, took longer. About 4 minutes.
The problem is likely somewhere else. Not sure yet.
I haven't turned on the logging for the spring bytecode scanning yet to know if that's where the time is going.
This environment has a mix of logging infrastructure (commons logging, java.util.logging, jetty logging, log4j, slf4j, and logkit), setting it up takes a bit of time (using slf4j to capture it all and route down to a single logging impl).