n-gram speed

[Denis Kuzmenok]

I have a database with n-gram field, about 5 millions documents. QTime
is  about 200-1000 ms, database is not optimized because it must reply
to  queries  everytime  and  data  are updated often. Is it normal?
Solr: 3.1, java -Xms2048M -Xmx4096M
Server: i7, 12Gb