PDFBOX-5660: optimize, as suggested by Valery Bokov, closes #380

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1930545 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/multipdf/Splitter.java

@@ -211,7 +211,8 @@ private void cloneStructureTree(PDDocument destinationDocument) throws IOExcepti
         PDNumberTreeNode srcParentTree = srcStructureTreeRoot.getParentTree();
         Map<Integer, COSObjectable> srcNumberTreeAsMap = PDFMergerUtility.getNumberTreeAsMap(srcParentTree);
         Map<Integer, COSObjectable> dstNumberTreeAsMap = new LinkedHashMap<>();
-        for (int p = 0; p < dstPageTree.getCount(); ++p)
+        int dstPageTreeCount = dstPageTree.getCount();
+        for (int p = 0; p < dstPageTreeCount; ++p)
         {
             PDPage page = dstPageTree.get(p);
             int sp1 = page.getStructParents();