Assuming you were getting good throughput before, it could be a few different things. Maybe your ISP is throttling you, though that would be an extremely harsh throttle. Or maybe the server that you're downloading from (or a router between you and that server) is very overloaded. Try choosing a different server. Have you tried rebooting your PC, too? It's surprising how many things that can fix. It's probably not malware, but maybe check for that, too, and look to see if some buggy program is using up all your bandwidth.

引用自 matt：

Assuming you were getting good throughput before, it could be a few different things. Maybe your ISP is throttling you, though that would be an extremely harsh throttle. Or maybe the server that you're downloading from (or a router between you and that server) is very overloaded. Try choosing a different server. Have you tried rebooting your PC, too? It's surprising how many things that can fix. It's probably not malware, but maybe check for that, too, and look to see if some buggy program is using up all your bandwidth.

Thank you for your response. For some reason it just fixed itself without rebbot.