Slow performance, sometimes crashes when find/replace on large files

Find/replace works fine on most files, but I encounter slower performance and a crash occasionally while operating on larger files. May need to update TextTrix.replaceSection

Exception in thread "Thread-6" java.lang.NullPointerException
at javax.swing.text.CompositeView.replace(Unknown Source)
at javax.swing.text.View.updateChildren(Unknown Source)
at javax.swing.text.View.changedUpdate(Unknown Source)
at javax.swing.text.FlowView.changedUpdate(Unknown Source)
at javax.swing.text.ParagraphView.changedUpdate(Unknown Source)
at javax.swing.text.View.forwardUpdateToView(Unknown Source)
at javax.swing.text.View.forwardUpdate(Unknown Source)
at javax.swing.text.BoxView.forwardUpdate(Unknown Source)
at javax.swing.text.View.changedUpdate(Unknown Source)
at javax.swing.plaf.basic.BasicTextUI$RootView.changedUpdate(Unknown Source)
at javax.swing.plaf.basic.BasicTextUI$UpdateHandler.changedUpdate(Unknown Source)
at javax.swing.text.AbstractDocument.fireChangedUpdate(Unknown Source)
at javax.swing.text.DefaultStyledDocument.setCharacterAttributes(Unknown Source)
at com.Ostermiller.Syntax.Colorer.processEvent(Colorer.java:287)
at com.Ostermiller.Syntax.Colorer.run(Colorer.java:172)

[Issue report ported from Trac.]