New Post: Stress test of XSSF proves exponential time (performance concerns)

Also, if you simply change XSSFWorkbook to HSSFWorkbook (Still using NPOI 2.0 beta)... these are the results

Start time: 5/15/2013 11:09:36 AM
[00:00:00.0270027] 0 rows written
[00:00:00.0540054] 10000 rows written
[00:00:00.0920092] 20000 rows written
[00:00:00.1160116] 30000 rows written
[00:00:00.1980198] 40000 rows written
[00:00:00.2220222] 50000 rows written
[00:00:00.2820282] 60000 rows written
(crash due to row limit)

The speed difference is concerning.

Now we can compare to NPOI 1.2.3 which must use HSSFWorkbook... these are the results

Start time: 5/15/2013 11:27:18 AM
[00:00:00.0180018] 0 rows written
[00:00:00.0380038] 10000 rows written
[00:00:00.0550055] 20000 rows written
[00:00:00.0880088] 30000 rows written
[00:00:00.1070107] 40000 rows written
[00:00:00.1900190] 50000 rows written
[00:00:00.2450245] 60000 rows written

This is even faster, though the fact that we are talking about tenths of a second is still good.