press CTRL, ALT and Delete together and choose task manager.
Click “More Details” (if visible)
Click the “Performance” tab
On a healthy PC, processor should be at rest (low useage), memory around a third or less ideally and hard drive under a third.
If this is the case and the internet is slow, your broadband may be at fault.
If the processor is high but disk and memory are not, click the CPU column and arrange highest to lowest, the task at the top is the reason your pc is running slow.
If memory and disk are high, it is likely you need more memory.
If just disk is high, it may be time to upgrade to SSD.