Acer Aspire 5 A515 family is running very slowly

The checks in more detail

and a disk showing near one hundred percent in use at idle points to a slow drive or a background task such as an update, an antivirus scan or cloud syncing. Open the Startup tab and disable programs you do not need at start-up, since a dozen launchers make a budget laptop crawl for the first ten minutes. Check storage: Settings, System, Storage shows how full the drive is, and a laptop with less than ten percent free slows down, so remove large files, uninstall unused apps and run Disk Cleanup.

Check memory: many Aspire 5 models have 8 gigabytes, which is tight for modern browsers, so close tabs, and consider whether the memory is upgradeable on your configuration. If the laptop has a hard disk, an SSD upgrade is the single biggest improvement. Keep Windows and the drivers updated through Windows Update and Acer's care software, but let updates finish, because they can hold the machine busy.

Heat slows the processor, so use the laptop on a hard surface and clean the vents with compressed air held at a distance with the laptop off. In Power Options, use the Balanced or Best performance mode on mains power and avoid Battery saver when you need speed. Run a malware scan, and check that you are not running two antivirus programs at once. If all of this leaves it slow, a reset of Windows with a backup first often helps.