Logstash grok

Hi Magnus,
I have just started exploring Logstash.
Currently trying to load a log file to elasticsearch, but it's taking a long time to create index.
Please help me understand how can we tune the config of the logstash.

File content is :
INFO : LM_36435 [Thu Apr 21 23:27:16 2016] : (20731|-1449096896) Starting execution of workflow [wf_test] in folder [Folder1] last saved by user [admin].

Config file :

input {

file {
path => "/logstash-2.1.1/conf/Infa_log/wf_test.log"
start_position => "beginning"
type => "infa_logs"
}
}

filter {

            grok {
                    match => [ "message","%{WORD:Severity} : %{WORD:Message_code} \[%{DAY:Day} %{MONTH:Month} %{MONTHDAY:Day_of_Month} %{HOUR:Hour}:%{MINUTE:Min}:%{SECOND:Sec} %{YEAR:Year}\] : \(%{NOTSPACE:Num}\) %{GREEDYDATA:Message}"
                    ]
                    }

}

output {

elasticsearch{
hosts => ["localhost:9200"]
index => "infa_log"
}

}

Regards,
Asrar