ArneBab/plugin-WoT-staging — comment on commit 986feb3bdd784dc990e77a9a95e7af3546333ce3
File:  line 0
By xor-freenet:

JavaDoc of StringBuilder: "This class provides an API compatible with StringBuffer, but with no guarantee of synchronization. This class is designed for use as a drop-in replacement for StringBuffer in places where the string buffer was being used by a single thread (as is generally the case). Where possible, it is recommended that this class be used in preference to StringBuffer as it will be faster under most implementations. "
Since you are always on a single thread here, use StringBuilder.