The wireless network speed (throughput) will usually be affected by these factors, so you can do some adjustments to mitigate these issues.

Interference – Interference of cordless phone, microwave or other electronic devices that utilize same 2.4 GHz radio frequency. Also the interference between wireless networks that use the same channel will reduce the network throughput as well.

Signal Blocking – Signal blocking by thick wall or other physical barriers especially at home.

Shared bandwidth – The bandwidth of wireless network is shared among wireless users, so the more users you have on the same network the slower network speed.

Distance – If you sit near wireless router/access point, you will get high and good network speed. However if another person joins the network sitting far from the wireless router/access point, the network speed of both computers will be dropped drastically. The rule is the further your location from the wireless router/access point, the slower your connection will be, and the distance will affect the network speed of other users also.

Mixed Network (802.11b/g) – In an 802.11b/g mixed network, you can get good network speed by using 802.11g wireless adapter if connecting alone, however once an 802.11b user joined the network, your network connection speed may be slowed by half or more.