Steps to Reproduce

1. run the attached zul

Current Result

it takes over 60s to show the page

Expected Result

speed up the performance

Debug Information

• One cause: unnecessary cell change
  in FormulaTunerHelper.extendCellRef(),
  sheet3!E4
  the original formula: VLOOKUP(C4,sheet1!C:I,6,0)
  the formula after insertion: VLOOKUP(C4,sheet1!C$1:I$65537,6,0)
  The 2 formula are actually equivalent but their string are not equal (!fexpr.getFormulaString().equals(exprAfter.getFormulaString())) is false, it triggers cell change and calling getDependent() which takes a long time.
• In FormulaEngineEx.adjustPtgs():
  Ptg[] tokens = org.zkoss.poi.ss.formula.Formula.create(fe.getPtgs()).getTokens();
  it only copies 2 bytes whose max value is 65535 (Excel97) but PtgShifter runs with EXCEL2007 which has larger max row. Such create() will reduce the max row to 65535