using GHDL and have problems with VCD dump option

GHDL is free simulator. I found this tool very useful. GHDL is also
capable simulating the free LEON processor. Presently, if the VCD
option is enabled, all signals of the design are recorded. This
impacts the performance and requires large disk space.

I generate my own form the VHDL code (example: probe_i2c_slv.vhd).
This way it is easy to select what signals to dump and on what time.
More details are at :
http://bknpk.no-ip.biz/I2C/leon_2.html