The following performance test was done with a 40MB flat file transforming from one file to 8 different output files. This test is done on a Lenovo T61 with 3GB of RAM and 2.o GHz Core 2 Intel Chipset:
All nine transformation was processed in 2:13 minutes.
Please see the document below for more performance tuning tips on your WTX maps:
ftp://ftp.software.ibm.com/software/websphere/integration/wdatastagetx/1120.pdf
Thys Michels Blog 