Why is my computer so slow?

Slowness usually comes from a short list of causes. Too many programs running at once, especially ones that launch at startup and lurk in the background, eat memory and processing power; a browser with dozens of open tabs is a common and underestimated hog. Too little RAM (memory) forces the computer to shuffle data to the much slower drive. A hard drive that is nearly full, cluttered, or beginning to fail slows everything down. And on older machines, accumulated junk, unnecessary startup apps, bloated software, and sometimes malware, all pile on. Restarting regularly, closing unused programs, trimming startup apps, and running a malware scan address a lot of it for free.

The most transformative fix for an aging computer is hardware: replacing an old mechanical hard drive with a solid-state drive (SSD). Traditional spinning drives are the biggest bottleneck in older machines, and an SSD, which has no moving parts and reads data far faster, can make a five-year-old laptop boot in seconds and feel genuinely new, typically for well under a hundred dollars plus a bit of installation. Adding more RAM is the second-best upgrade if the machine is starved for memory. Before buying a new computer, it is worth asking whether an SSD and a memory bump, often a fraction of the cost, would solve the problem, because for a huge share of slow computers, they do.