There have been plenty of times when my Windows PC has felt slow online, and my first instinct is usually to blame the connection. I'll run a speed test, which is easier now that Windows can surface a speed test from search, and check whether I'm actually getting the speed that I'm paying for. If the numbers look off, the next move is obvious: reboot the PC, reset the Wi-Fi router and modem, and hope the problem clears itself up.