Search query speed

The speed of particular query has gone from about 42 msec to 66 msec without any changes. How do I go about troubleshooting what may have happened? And how do I improve that speed? Thanks

Re: Search query speed

There is a .NET app that is calling solr. I am measuring time span using .NET provided methods. It used to take about 42 msec and it started taking 66 msec from the time to compose the call and query solr, get results and parse them back. Interestingly today it was close to 44 msec. I am testing us