Your PC is slow:
is it a virus?

Hardly ever. Among the computers brought in for being slow, viruses account for a minority of cases: the usual culprits are a worn-out mechanical hard drive, not enough memory for what you're asking of it, or too many programs starting up with the system. The quick way to rule it out without opening anything dodgy: open Task Manager and see what's at 100%. If it's the disk or the memory, it isn't malware; it's a component that's no longer up to the job. Malware leaves different, more visible traces: windows or warnings that pop up without you doing anything, your search engine or home page changed for no reason, contacts receiving emails you didn't send, or the fan running flat out while the computer appears to be idle. If you see none of those signs and the problem has been constant for months, bet on hardware or configuration rather than a virus: that's what the diagnosis confirms in most of the computers we check.

Look at the pattern, not a single sign: slow start-up, the drive light blinking non-stop and the feeling that the computer is "thinking" before opening any program, even though the mouse moves normally. Task Manager confirms it: the disk column shows 100% while the CPU barely moves, exactly the opposite of what happens when the bottleneck is something else. There's one sign that leaves no room for doubt and is worth stopping everything for: rhythmic clicks, grinding or whirring that wasn't there before. That isn't the system being slow; it's a mechanical drive physically failing, and every hour it stays on brings closer the moment it won't start at all. If you hear that, the priority changes: before looking at performance, back up whatever matters to you. If the drive is already an SSD, this diagnosis doesn't apply and you need to look at memory or start-up.

Almost always, if the mechanical drive is the bottleneck and the rest of the computer is up to it: a decent processor and memory paired with a spinning disk is the most wasted combination there is, and the difference is noticeable from the very first start-up. Whether it pays off isn't decided by a fixed figure but by three questions: whether the computer can take more memory later if needed, whether the operating system you need is still compatible with that hardware, and whether the other components have several years of life left in them or the drive is just the first item on a long list of replacements. If the computer already has an SSD and is still slow, replacing it again won't fix anything: the problem lies in memory, start-up or, more rarely, malware. Migrating the system to the SSD without reinstalling from scratch is standard practice and keeps your programs and settings, so there's no need to start over.

One, and with an up-to-date operating system that matters more than the antivirus brand. Installing two at once doesn't double the protection: they fight over access to the same files, the computer slows down and sometimes one antivirus blocks the other, thinking it's the suspicious one, which leaves gaps with no real monitoring. The antivirus built into Windows is more than enough for normal use if the system receives its updates; the real step up in protection doesn't come from adding a second layer of antivirus, but from keeping the system and programs up to date, making regular backups and being wary of what arrives by email or phone before clicking. If your computer is part of a company network, that centralised management does justify an additional solution designed for the purpose, which is different from installing two standalone desktop programs that compete for the same resources.

Very little, and several actually make worse the problem they claim to solve. The pattern is always the same: they also install themselves at start-up — precisely what makes a computer slow — they show a scan with dozens of "critical errors" that are really harmless registry entries, and behind that alarm they offer the paid version as the only way out. If an advert promises to speed up your PC by a specific percentage, that's marketing with made-up metrics, not a measurable fact: no cleaning program recovers the performance lost to a worn-out mechanical drive or replaces missing memory. The only things in that category that really make sense are what you can already do for free with the system's own tools: free up disk space, review what starts automatically and keep the system updated. If you already have one of these programs installed and don't remember choosing it, now is a good time to uninstall it and see what changes.

It's the brute-force solution, and sometimes it's the right one, but never the first step. Before formatting you need a verified backup of your data — genuinely verified, not just started — because if something goes wrong halfway through there's no going back. And if the real cause was a worn-out mechanical drive or a lack of memory, formatting changes nothing: the system starts up clean, runs well for a short while and slows down again within days, because the hardware is still the same. Formatting makes sense when the system is so clogged with programs, leftovers and settings built up over years that cleaning it bit by bit would take longer than starting from scratch, or when there's a serious suspicion of malware that a normal scan can't resolve. Outside those cases, it's quicker and less risky to diagnose first what's failing and fix just that part, which is exactly what we do before suggesting a format.

It depends on what's needed, not just on the list of tasks. Software maintenance — cleaning up start-up, updates, checking disk space — is done the same day, because it doesn't depend on parts or orders. If the drive needs replacing and the system migrating, the time is mainly set by the amount of data to move and whether the migration is done by cloning the old drive or installing from scratch: cloning is usually quicker, but it requires the source drive to still read properly, so if it's already making noises it isn't an option. If you need to work on the computer during those days, say so when you drop it off: it's often possible to prioritise getting it working with the bare minimum on the same day and finish the rest without you depending on it. What almost always stretches a timescale is finding something unexpected when the computer is opened up, not the repair itself.

There's no fixed threshold in euros because it depends on three things that vary from one computer to another: how many parts are needed at once — a drive is not the same as a drive plus memory plus a battery — whether those parts are still being made for that model, and whether the computer, even if it works perfectly, still supports the operating system and programs you need to use today. A laptop with just one weak component and otherwise in good health is usually worth repairing without hesitation. A computer that needs several parts at once, no longer receives security updates from the manufacturer, or for which spares are already hard to find, enters territory where you need to compare before deciding. We give you that comparison with real figures for the computer in front of us, not a generic table, and if the conclusion is that it isn't worth repairing, we'll tell you so even if it means not selling you anything.