This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
There shouldn't be a performance hit. The bigger problem is unless they are simple utility methods then the design is probably poor. Minor things like static vs non-static rarely affect performance in a noticeable manner. Poor design, and IO usually dominate. As always don't guess, measure!