Is it better to leave a lamp with a CFL on than to turn it off and on serval times a day?

It is generally more energy-efficient to turn off a CFL (compact fluorescent lamp) if you plan to be away for more than 15 minutes, as the energy consumed during start-up is minimal compared to leaving it on for extended periods. Frequent on-and-off cycling can shorten the lifespan of a CFL, but this is not as significant as the energy savings from turning it off. Therefore, it's best to switch it off when not in use for longer durations.