The current Java Class Library for access to FITS files was designed for the VLT Data Flow System pipeline subsystem. ... all types of headers are decoded, . ... As the code has not been optimized, data access is slow e.g. on a 160 MHz machine and no JIT, 32-bit real images are read at 50k values/sec, 16-bit integer images at 80k values/sec while table data are read at 10k values/sec. FITS keywords are decoded at a rate of 2-3k keywords/sec depending significantly on their types. ...