Does the dumping of simulation data using *.wlf make simulation slower in Questa Sim?

The answer is yes.
In my project, ‘log -r /top/dut/*’ took 16% of simulation performance.
The recorded waveform is important for debug, so I recommend to log only the relevant instances for your simulation.
Look for ‘profile on’ and ‘profile off’ in Questa help. It may help you to understand which process takes simulation performance.
Beeri