The illusion of multitasking improves performance.

From Srna et al.:

With technological advancements, the desire, ability, and often necessity to multitask are pervasive. Although multitasking refers to the simultaneous execution of multiple tasks, most activities that require active attention cannot actually be done simultaneously. Therefore, whether a certain activity is considered multitasking is often a matter of perception. This article demonstrates the malleability of what people perceive as multitasking, showing that the same activity may or may not be construed as multitasking. Importantly, although engaging in multiple tasks may diminish performance, we found that, holding the activity constant, the mere perception of multitasking in fact improves performance. Across 32 studies (30 of which had performance-based incentives) containing a total of 8,242 participants, we found that individuals who perceived an activity as multitasking were more engaged and consequently outperformed those who perceived that same activity as single tasking.