With
SetDirectory["~/Downloads"];
ifile = "test.xls";
TimeConstrained[idata = Import[ifile, {"Data", 1}], 5];
I can achieve the desired result of importing the first page of the spreadsheet in under 5 seconds.
When the same data are reformatted (Excel "Save As ...") to ODS format
SetDirectory["~/Downloads"];
Clear[idata];
ifile = "test.ods";
TimeConstrained[idata = Import[ifile, {"Data", 1}], 60];
times out.
Is ODS Import[] broken? Does anybody else have this issue?