configuration - duplication in parsing spring context -

nowadays i've got know spring mvc. about

context:component-scan 

and

mvc:annotation-driven 

and

tx:annotation-driven 

in spring config xml

here question. know, "context:component-scan" scans beans. , heard, mvc:annotation-driven, tx:annotation-driven"s scan beans.

i think not efficient , not reasonable.

why scan twice, 3 times.

is there way avoid duicate parsing?

any answer appreciated. thank you.

in opinion, scanning process not twice, 3 times think.
declare related beans think.
please refer below summarize , find out how differences.

<context:annotation-config>  declares support general annotations such @required, @autowired, @postconstruct, , on.  <context:component-scan>  can <context:annotation-config> <context:component-scan> scans packages find , register beans within application context. 

<mvc:annotation-driven />   enables spring mvc @controller programming model ,  declares explicit support annotation-driven mvc controllers (i.e. @requestmapping, @controller, although support default behaviour), adding support declrative validation via @valid , message body marshalling @requestbody/responsebody. 

<tx:annotation-driven /> provide transaction-manager instace directly within element. annotation-config , component-scan won't.