To super oversimplify this for explanation, let's say our quantum computer runs today with a clock cycle of 50 megahertz.
The quantum computer is able to do certain tasks in fewer clock cycles but since we measure time in seconds a regular 3.2Ghz 8 core CPU today would perform 5,000x the clock cycles per second.
If quantum is going to scale and work is still TBD but saying they are slower in seconds isn't a fair way to grade. They could be 1000x faster in clock cycles and still 5x slower in seconds today.
Link on IBM Quantum https://indico.cern.ch/event/719844/contributions/3019718/at...