For a consumer, it can simply be a general sluggishness of response from the computer. It's possible that a home-user may notice that the computer seems hotter than usual, but more so on a laptop than a home desktop because on a laptop, when you type your hands are closer in contact with the overheating CPU (Central Processing Unit) that Cryptojacking uses to perform the functions.
Within the IT Support Los Angeles Community, there are tons of low-level Break & Fix IT services firms - that wait for something to break and then come out and fix it IT consulting services at that level concern themselves with 'one-off' issues, not the ongoing health of the network the way a Managed Services Provider does. It takes a 24/7 'hands-on' proactive Managed IT Services firm that is extremely familiar with the way your network performs to spot the anomalies in the behaviors. As usage is analyzed on a regular basis, the IT HelpDesk technicians can easily see that a network is working harder than usual - with no corresponding rise in user activity. Any qualified IT support and services worker knows that any anomalies must be examined, because even if it's not a problem now, the good IT support technician knows that it may well become an issue if left unchecked.
Here at IT Support LA, we have never had a successful cryptojacking of any of our clients, but since the 'Hackers vs. Cybersecurity' contest is like an ongoing game of 'Whack-A-Mole', we stay ever-vigilant for unusual network activity events - which can happen for a number of reasons, and can indicate different types of attacks. Even if it isn't a cryptojacking or an attempted breach, it means something, especially if it's coupled with a decrease in network performance.