My wife has a Lenovo x100e. She is currently having serious network speed issues. Trying a speed test at speedtest.net, her results are ping of 23ms, 1.19Mbps download/3.2 upload.
Her CPU spiked from about 30% to about 75%, but not much higher.
She's tried disable/ enable the network adapter, and that hasn't helped.

On MY laptop I get 16-20Mbps download, so it's not the router, modem, or ISP.

Her computer's specs are:
CPU AMD Athelon Neo X2 Dual Core L335 1.60GHz
BIOS: Lenovo 6xet49ww (1.32) 6/13/2011
Windows 7 Home Premium
2GB RAM
Anti-virus:Avast(up to date)
All current Windows updates are installed
Using Windows Firewall
Windows Defender is active